Dynamic data transport between enterprise and business computing systems

ABSTRACT

A data transport system includes nodes configured to communicate with local devices via independent native protocols and to store a metadata schema that defines a data interface for process variables. The data transport system includes a computing system programmed to communicate with an application and the nodes using a media independent messaging service that is layered over respective communication protocols associated with the application and the nodes. The computing system receives, from the nodes, metadata corresponding to the data interface and dynamically render a web application programming interface (API) that allows users of the application to access the process variables.

TECHNICAL FIELD

This application is generally related to a dynamic data transporttechnology that provides a seamless and self-configuring connectionbetween an enterprise system and business systems.

BACKGROUND

Distributed computing systems are used in many business enterprises. Abusiness may conduct operations at many locations. Each location mayperform a variety of functions including planning, manufacturing, andsales. Information from each location may be distributed in real-timeacross the network. Present systems require extensive programming ofdevices throughout the business enterprise to support information acrossthe network. Further, any changes to devices connected to the networkrequire programming changes to devices located throughout the network.In addition, implementation requires coordination among the variousdevices in the network.

SUMMARY

A data transport system includes at least one node configured tocommunicate with local devices via independent native protocols and tostore a protocol agnostic metadata schema (PAMS) that defines a datainterface for process variables. The data transport system furtherincludes at least one computing system programmed to communicate with atleast one application and the at least one node using a mediaindependent messaging service (MIMS) that is layered over respectivecommunication protocols associated with the at least one application andthe at least one node. The at least one computing system is programmedto receive, from the at least one node, metadata corresponding to thedata interface and dynamically render a web application programminginterface (API) that allows users of the at least one application toaccess the process variables. The at least one computing system isfurther programmed to, responsive to requests from the at least oneapplication to access the process variables, transfer the requests tothe at least one node and transfer responses from the at least one nodeto the at least one application.

The PAMS may be encoded in extensible markup language (XML). The atleast one application may be executed on a terminal that is incommunication with the at least one computing system. The at least onenode may be identified by an identifier that changes when the datainterface changes. The at least one computing system may be furtherprogrammed to query the at least one node for the identifier and,responsive to the identifier not matching a stored identifier, requestthe at least one node to transfer the metadata corresponding to the datainterface and re-render the web API. The PAMS may be generated based onone or more enumerated types defined in one or more source code filesfor the at least one node. The PAMS may be configured to bind instancesof the process variables to a record that describes the data interfaceof the process variables. The at least one application may access theprocess variables by requesting respective values associated with theprocess variables and by setting respective values associated with theprocess variables using a message structure defined by the MIMS. Theprocess variables may be mapped to software variables used by the atleast one node.

A node for use in a data transport system includes a controllerprogrammed to store a protocol agnostic metadata schema (PAMS) thatdefines a data interface for process variables. The controller isfurther programmed to communicate with a server over a firstcommunication channel using a media independent messaging service (MIMS)layered over a first communication protocol and communicate with onemore process devices via a native protocol that is independent of theMIMS. The controller is further programmed to transfer metadataassociated with the data interface to the server and respond to requestsfrom the server for access to process variables that are defined in thedata interface.

The PAMS may be encoded in extensible markup language (XML). The PAMSmay be generated based on one or more enumerated types defined in one ormore source code files for the node. The PAMS may be configured to bindinstances of the process variables to a record that describes the datainterface of the process variables. The controller may be configured tocommunicate with at least one other node over a second communicationchannel using the MIMS layered over a second communications protocol andprogrammed to transfer messages using the MIMS between the firstcommunication channel and the second communication channel. Thecontroller may be programmed to identify the node by an identifier thatchanges when the data interface changes.

A host services gateway for use in data transport system includes acontroller programmed to establish a communication connection with atleast one node. The controller is further programmed to receive anidentifier for a protocol agnostic metadata schema (PAMS) that defines adata interface for process variables of the at least one node. Thecontroller is further programmed to request, responsive to theidentifier not matching previously stored identifiers, the at least onenode to send metadata corresponding to the data interface. Thecontroller is further programmed to dynamically render a web applicationprogramming interface (API) from received metadata and expose the webAPI to at least one application.

The controller may be further programmed to transfer values of processvariables between the at least one application and the at least one nodeaccording to the web API. The controller may be further programmed tocommunicate with the at least one node and the at least one applicationusing a media independent messaging service (MIMS) that is layered overrespective communication protocols associated with the at least oneapplication and the at least one node. The respective communicationprotocols may include hypertext transfer protocol (HTTP) that isassociated with the at least one application. The controller may befurther programmed to store the metadata and web API associated with theat least one node.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a diagram of a system for Enterprise Requirement Planning(ERP).

FIG. 2 depicts a possible message structure for retrieving informationfrom a node.

FIG. 3 depicts a possible message structure for setting data values in anode.

FIG. 4 is a flowchart for a possible sequence of operations for a hostservice gateway and a node for transferring an Application DescriptorSheet.

FIG. 5 is a flowchart for a possible sequence of operations forgenerating the Application Descriptor Sheet.

FIG. 6 is a possible workflow for generating the Application DescriptorSheet.

FIGS. 7A and 7B depict a block diagram of a possible systemconfiguration in which nodes communicate with devices over a localnetwork.

FIG. 8 is a block diagram of a possible connection configurationincluding master and slave nodes.

FIG. 9 is a possible message structure for a Media Independent MessagingService frame.

FIG. 10 is a possible structure for a protocol type message field.

FIG. 11 is a possible structure for a media frame control message field.

FIG. 12 is a possible structure for a control and status word messagefield.

FIG. 13 is a possible structure for a status message field.

FIG. 14 is possible structure for a frame tag message field.

FIG. 15 depicts a communication transaction in which a protocol framelength is the same as a media frame length.

FIG. 16 depicts a communication transaction in which the protocol framelength is less than the media frame length.

FIG. 17 depicts a communication transaction for a single-frame tomulti-frame forwarding use case.

FIG. 18 depicts a communication transaction for a multi-frame tosingle-frame forwarding use case.

FIG. 19 depicts a block transfer from master to slave.

FIG. 20 depicts a block transfer from slave to master.

FIG. 21 depicts possible status field values for error notification.

FIG. 22 depicts a possible structure for an error frame.

FIG. 23 depicts a possible message frame header.

FIG. 24 depicts a possible configuration of a communication networkhaving master and slave devices.

FIG. 25 depicts a slave-master node and possible communicationconnections.

FIG. 26 depicts a possible structure for a device descriptor workmessage field.

FIG. 27 depicts a possible structure for a property hash record.

FIG. 28 depicts a possible structure for an instance identifierbit-field.

DETAILED DESCRIPTION

Embodiments of the present disclosure are described herein. It is to beunderstood, however, that the disclosed embodiments are merely examplesand other embodiments can take various and alternative forms. Thefigures are not necessarily to scale; some features could be exaggeratedor minimized to show details of particular components. Therefore,specific structural and functional details disclosed herein are not tobe interpreted as limiting, but merely as a representative basis forteaching one skilled in the art to variously employ the presentinvention. As those of ordinary skill in the art will understand,various features illustrated and described with reference to any one ofthe figures can be combined with features illustrated in one or moreother figures to produce embodiments that are not explicitly illustratedor described. The combinations of features illustrated providerepresentative embodiments for typical applications. Variouscombinations and modifications of the features consistent with theteachings of this disclosure, however, could be desired for particularapplications or implementations.

Plant productivity due to automation and communication technology havemade remarkable advances over the past several decades. Advances indatabase architecture and Enterprise Requirement Planning (ERP) systemshave contributed to a streamlining of business practices in manyindustries. ERP systems may be used to track resources and status oforder. The ERP system may aid in sharing information between businessfunctions.

Advances and cost reductions in cloud computing, hardware, andnetworking devices have led to a prevalence of an Internet of Things(IOT) technology. As a result, methods of deploying this technology toconnect ERP systems to plant operations facilities may be realized.

ERP systems may connect to real-time data generated in operations inseveral ways. The real-time data may include data generated in a plantor factory during production. The real-time data may include informationrelated to inventory and production output. The real-time data mayinclude any process variables used to measure and/or control a process.The real-time data may include manufacturing line data points that areobtained from sensors. For example, the sensors may include an imagesensor such as a Charge-Coupled Device (CCD), an optical sensor such asa bar code scanner, a temperature sensor, a pressure sensor such as atransducer or a pressure switch. Additional sensors measuring electricalproperties such as voltage, current, and/or power may also providemanufacturing line data points. ERP systems may be implemented by SystemIntegrators. The System Integrators may have unique knowledge andcapabilities for integrating the real-time data of the operations intothe back-office ERP or Manufacturing Execution System (MES).

There are four primary methods of connecting the back-office ERP systemto the physical plant data monitoring systems. The methods includedatabase integration, direct integration, Enterprise ApplianceTransaction Modules (EATM), and custom integration solutions. Themethods are briefly described herein.

ERP systems may connect to the physical plant using staging tables in adatabase. Data must be entered into the system by operators orautomation systems. The process typically requires a large amount ofcustomization and data entry. Much of the data staging may be performedmanually using barcode scanners or terminals.

Some end-to-end solutions that are available may integrate machine datadirectly into an existing ERP vendor's solution. Such solutions mayrequire extensive product coordination and alliances between equipmentvendors and the ERP vendor. Such vendors typically require the purchaseof an “all or nothing” strategy for upgrading the physical plant. As aresult, these types of systems may be used in “greenfield”implementations for the physical plant.

In the case of an EATM, a vendor may supply an edge router/server thatcan communicate as a bridging device between the machines of interestand the ERP. In this case, there is no requirement for coordinationbetween the devices in the physical plant and the ERP. The EATM vendorimplements all the interface requirements necessary to achieve thissolution.

Custom integration solutions represent the highest value to theend-user. Custom integration solutions are customized for each specificcustomer. Custom integration solutions generally have the highestinitial cost and may require a high-level of maintenance costs. Themethods described can be inflexible with respect to adapting to newtechnologies.

While custom integration solutions can provide the customer with asuitable connection of the ERP to the physical plant, several issues maybe present. First, such systems use a static data model. With a staticdata model, server and network connectivity software must change whenthe data model changes. Second, the solutions are monolithic in nature.In general, a specific solution is implemented and any changes to thebusiness practices or operations requires a complete or partial systemsoftware overhaul. Third, the solutions are an all-or-nothingintegration and are not very scalable. The end-user is usually facedwith a decision to implement all or nothing to connect the physicalplant to the ERP. Such solution may only be practical for a new plant ora plant that is undergoing an extensive overhaul. Fourth, the lack ofscalability entails a high initial investment in plant upgrades andcustom software. High maintenance costs may be incurred for customreport generation and server maintenance. The system presented hereinattempts to address the limitations of previous connection systems.

A connectivity system is developed to incorporate a dynamic datatransport technology that allows a seamless and self-configuringconnection between the enterprise and business systems. The connectivitysystem may include a Web Services Application Programming Interface(API) (Web Services API). The connectivity system may include anApplication Server and a Host Services Gateway (HSG) that may cooperateto implement the Web Services API. The connectivity system may includeone or more Solutions Gateway Devices. The Solutions Gateway Devices mayinclude a processor system that executes one or more applicationsreferred to as Nodes.

FIG. 1 shows a graphical depiction of a data transport system orconnectivity system 100 and how it interacts with the systemenvironment. FIG. 1 also includes some of the Nodes interconnected in acascaded arrangement.

The data transport system 100 may include a Web Services API 102 that isimplemented as part of a Host Services Gateway 106 and an ApplicationServer 104. The Host Services Gateway 106 and the Application Server 104may be executed as applications or programs on a computing system 108.The connectivity system 100 may include a plurality of plant devices orsystems 112. The plant devices 112 may include devices that are operatedwithin a plant or station. For example, the plant devices 112 may bepart of a factory automation system or process control system. The plantdevices 112 may represent the output of various sensors and productionsystems. The plant devices 112 may also be defined by input variablessuch as operating setpoints. The plant devices 112 may definemanufacturing line and process data points.

The plant devices 112 may communicate with one or more SolutionsGateways or Nodes 110A, 110B, 110C. Each of the Nodes 110 may include amicroprocessor system including volatile and non-volatile memory forstoring programs and data. Volatile memory may include storage elementswhose contents are lost when power is no longer applied, such asrandom-access memory (RAM) devices. Non-volatile memory may includestorage elements and devices whose contents are maintained when power isno longer applied. Non-volatile memory may include, but is not limitedto, read-only memory (ROM), FLASH memory, magnetic storage media such asdisk drives or tape drives, and Universal Serial Bus (USB) drives. Insome configurations, one or more of the Nodes (e.g., 110A) may beexecuted as a program or application on the computing system 108. Insome configurations, a plant may have one Node that communicates withall the plant devices 112 within the associated plant or facility. Insome configurations, Nodes may be cascaded such that one of the Nodes(e.g., 110D) communicates with plant devices 112 and communicates withanother Node (e.g., 110A). The Nodes may be characterized as Master orSlave Nodes depending on a position within the communication chain.Communications between the Nodes 110 and the plant devices 112 may becharacterized as a native transport protocol. The Nodes 110 (or hardwarethat the Nodes are implemented on) may include hardware and software tosupport communication via the native transport protocol. In the plantenvironment, there may be a wide range of native transport protocols.For example, the plant devices 112 may communicate over an RS232channel, an RS 485 channel, a USB channel, a parallel data channel. Theplant devices 112 may communicate via a wireless communication channelsuch as Bluetooth. The plant devices 112 may communicate over a wired orwireless Ethernet link as defined by Institute of Electrical andElectronics Engineers (IEEE) 802 family of standards. For example, IEEE802.11 may include all variants of the 802.11 specification such as802.11 a/b, n, g, etc. The plant devices may communicate with a varietyof protocols such as Transmission Control Protocol/Internet Protocol(TCPIP). The plant devices may communicate with various wirelessstandards such as WiMax, cellular, ZigBee. The plant devices 112 maycommunicate with industrial communication protocols such as Modbus,Profinet, or other industrial control protocols. The native transportprotocol may be selected at the plant level to be most suitable for theprocess or production environment. The native transport protocol mayinclude Peripheral Component Interconnect (PCI) interfaces. PCIinterfaces may include all variants such as Peripheral ComponentInterconnect express (PCIe), Peripheral Component Interconnect eXtended(PCI-x), etc. The Nodes 110 may support multiple native transportprotocols depending on the number and type of plant devices 112 that areconnected.

The Nodes 110 may be configured to communicate with the Host ServicesGateway 106. Communication between the Host Services Gateway 106 and theone or more Nodes 110 may be via a Media Independent Messaging Services(MIMS) adaptation layer. The MIMS adaptation layer may also be used as adata link layer (DLL). The MIMS adaption layer may be implemented as asession layer over an existing media driver layer. For example, themedia driver layer of the Open System Interconnection (OSI) model isknown as the Media Access Control (MAC) and Data Link Layer (DLL). Theimplementation may be transparent with respect to the existing MAC andDLL for existing media. The MIMS abstraction layer may efficientlyabstract any media dependencies and allow the data transport in aseamless fashion on any media. The MIMS adaption layer may be athin-server protocol that can be implemented on constrained devices. TheMIMS adaption layer may be configured to provide a media independent wayto transport process data between the Nodes 110 and the Host ServicesGateway 106.

The Host Services Gateway 106 may be configured to communicate with anApplication Server 104. In some configurations, the HSG 106 and theApplication Server 104 may communicate via an Ethernet connection andprotocol. In some configurations, the HSG 106 and Application Server 104functions may be implemented in the same server or computing system 108.The computing system (e.g., 108) implementing the HSG 106 may include amicroprocessor system including volatile and non-volatile memory forstoring programs and data. Volatile memory may include storage elementswhose contents are lost when power is no longer applied, such asrandom-access memory (RAM) devices. Non-volatile memory may includestorage elements and devices whose contents are maintained when power isno longer applied. Non-volatile memory may include, but is not limitedto, read-only memory (ROM), FLASH memory, magnetic storage media such asdisk drives or tape drives, and Universal Serial Bus (USB) drives. Thecomputing system (e.g., 108) may include hardware and software tosupport communication with other devices (e.g., Nodes 110). For example,the computing system 108 may include hardware and software to supportwired and wireless Ethernet connections.

The Application Server 104 may provide facilities for a Web API and theresources to run the Web API. The computing system (e.g., 108)implementing the Application Server 104 may include a microprocessorsystem including volatile and non-volatile memory for storing programsand data. Volatile memory may include storage elements whose contentsare lost when power is no longer applied, such as RAM devices.Non-volatile memory may include storage elements and devices whosecontents are maintained when power is no longer applied. Non-volatilememory may include, but is not limited to, ROM, FLASH memory, magneticstorage media such as disk drives or tape drives, and USB drives. TheApplication Server 104 may be programmed to dynamically extract the datamodel from a set of nodes and render them as a Web API.

The Application Server 104 may be further configured to communicate overone or more internet or cloud connections 114 (114A, 114B, 114C). Thesystem may be configured to communicate with one or more computingdevices 116. The computing devices 116 may include tablets 116C, mobilephones 116A, and desktop/laptop computers 116B. The computing devices116 may be configured to access one or more of the internet connections114. The Application Server 104 may be configured to communicate withthe computing devices 116 through the internet connection 114. Thisallows the computing devices 116 to interact with the Application Server104 from any location that has access to the internet connection 114.The Application Server 104 may be configured to support TCP/IPcommunication over the Internet.

Each level of the connectivity system 100 may include programmablecomputing devices. In a traditional system design, software/firmwarechanges at one level may necessitate changes to the other connecteddevices. As a result, software and hardware changes must be carefullyorchestrated with all the computing devices to ensure that there is nodowntime or compatibility issues. This traditional model makes updatingthe system costly and time consuming. Disclosed herein are technologiesfor improving the operation of the connectively system 100.

The two underlying technologies for the connectivity system 100 are adynamic data model and a network abstraction layer. The dynamic datamodel abstracts the data in a way which allows any machine toautomatically configure its data interface to another machine. Thenetwork abstraction layer allows the data communication to occur in aprotocol independent fashion.

Existing systems typically utilize a static data model. A static datamodel may be one in which the data model does not change onceimplemented. The data model may describe the data and characteristics ofthe data such as format, units, and resolution. The static data modelmay be implemented in each level of the connectivity system. Forexample, a Node may generate a specific data element and transfer thedata element to the HSG. The HSG may transfer the data element to theApplication Server which in turn transfers the data element to theInternet-connected computing devices. With a static model, each devicemust know the characteristics of the data element. For example, each ofthe devices may need to be programmed to extract the data from aparticular data message that is transferred over the network. Suchcharacteristics may be coded into each system. As a result, changing adata element causes a ripple effect of software changes throughout thesystem. For example, if a low-level module changes the format of a dataelement, all modules that rely on the data element may need to bereprogrammed to support the new format. In the solution presented,changes are made at the Node level which then has the capability toreport the changes up through the system. In this manner, changes aremanaged automatically and Nodes change or as new Nodes are added.

An improved approach is to define a dynamic data model. The dynamic datamodel can assist in automating the connectivity. Using the dynamic datamodel, a system architect may identify and specify the customerrequirements to affect a solution. The solution may be implemented atthe Node 110 level of the connectivity system 100. Software for thesolution may be marked up. A schema may be generated for the markup andstored in the Node 110. The schema may define an outline or model of thedata associated with each Node 110. The schema may definecharacteristics of the data within the model.

The schema from Node 110 may be consumed at runtime by theinfrastructure (e.g., HSG 106, Application Server 104, User InterfaceServers, computing devices 116). It is observed that with thisarchitecture that data model or interface changes at the Node level areautomatically passed on to the other levels. As a result, new controland monitor processes can be added at the Node level and be quicklyrepresented at the other levels. New features are essentiallyplug-and-play into the existing infrastructure. When changes are made atthe Node 110 level, the schema is updated and transferred to othermodules to reflect the changes. The modules may implement a schemadecoding routine to determine the data elements that are present in theschema.

To achieve the dynamic data model, the connectivity system 100 maydefine a Protocol Agnostic Metadata Schema (PAMS) that allows the HostServices Gateway 106 to abstract the data model for any of the connectedNodes 110. The data model may be independent of any protocol or mediaused for communication between elements. The data model may rely on ametadata abstraction (also referred to as a schema). The schema maydescribe a format for the data associated with each of the Nodes 110.

The PAMS model may be derived by implementing a software solution or setof software solutions based on customer requirements and specifications.The software may be marked up to identify data that is to be included inthe PAMS model. The markup may be scanned during the software build toautomatically generate a schema that describes meta-data of the datamodel. The schema may then be used at runtime to allow theinfrastructure to determine how to communicate to the control andmonitor Nodes 110. The schema registration and data communications mayoccur between the Web Services API 102 and the control/monitor Nodes110. The communication transactions may be mediated by the HSG 106.

The dynamic data model allows a HSG 106 to acquire the schema from eachof the Nodes 110. The schema may be received and read by the HSG 106.This allows the HSG 106 to configure itself to establishprotocol-independent data management services with each of the Nodes110. The dynamic data model further allows the developer at the Node 110level to decide which data variables are exposed to the other levels.Variables from the software may be made visible to the other modules inthe system by updating the schema that is stored with each of the Nodes110. Variables that are not exposed are not accessible.

Most modern applications communicate via some standard or proprietarymedia interface. In many cases, the link-layer protocol is based on somegenerally accepted standard. Also, there are many instances where theprotocol is based on a proprietary interface. It is desirable toabstract away the protocol and media connections by introducing asession layer. This level of abstraction allows the existing interfacesand methods of communications to be preserved. The network abstractionlayer may also allow for a seamless method for communicatingschema-derived information over any communication channel.

A Media Independent Messaging Service (MIMS) may be defined for theNetwork Abstraction Layer. The MIMS may be a session layer protocol thatis layered onto any existing media or protocol. The usage of the MIMSallows the Nodes 110 to virtualize the interface to the HSG 106. TheMIMS may also provide a common interface for communicating with theNodes 110.

The PAMS may define a data model for each of the Nodes 110. The Nodes110 may be programmed to store the PAMS and to transfer the PAMSinformation to the HSG 106. The PAMS may define a data model thatsufficiently identifies data from the Nodes 110 such that the HSG 106can make use of the data. The advantage of the system is that the PAMSis provided by the Nodes 110 and any changes to the data structures aredescribed by the PAMS. The Node 110 may resend the PAMS to the HSG 106and the changes may be automatically incorporated in the HSG 106 andpropagated through the communication system. This eliminates the needfor reprogramming the HSG 106 when data from a Node 110 is changed.Further, additional Nodes 110 can easily be added.

The PAMS model may define a property-type pair for all instances of thedata elements. Any instance of data may be modified or queried using theproperty-type pair. A property may be a unique record that is bound toan instance of data. The instance of data may be the represented as theactual data value. The data type may represent the structure and formatof the data value.

The structure of a data instance may be represented by a type. The typecan take on any programming primitive type, such as INT, FLOAT, CHAR,SHORT, LONG, etc. A collection of many primitive types may be allowed.The collection of many types as a single type may be called a RECORD.Custom types may also be allowed. A custom type may be an alias of aprimitive or RECORD type. The custom type may be specified by the nodearchitect or developer.

For example, consider an instance of pressure in a vessel in units ofpounds per square inch (PSI). The Node 110 may sample an associatedsensor to obtain a pressure reading, for the vessel, as 200.5 PSI. Theinstance of data in this case is the pressure reading for the vesselmeasured as 200.5 PSI. The data type for this example is represented asa floating-point number or a FLOAT type.

The constituent parts of a PROPERTY may be a PROPERTY ID and a PROPERTYNAME. The PROPERTY ID may be a unique number that is bound to a datatype or instance. The PROPERTY NAME may be a string that is used tolabel the PROPERTY.

For example, consider a data instance that is associated with aPROPERTY. The PROPERTY NAME may be “Pressure_in_tank_1.” The PROPERTY IDmay be assigned a hexadecimal-value of 0x10. The type for this PROPERTYmay be a FLOAT type. The FLOAT type may be represented as an IEEE 754floating point number. Table 1 shows an example of the PROPERTY-TYPE forthis entry.

Another data point may describe an integral number that represents thetotal number of valves present at the particular Node. Table 1 includesa description of the total number of valves for this example. In thisexample, another PROPERTY may be introduced. The property may be named“total_number_of_valves”. The property ID for this property may beassigned a hexadecimal-value of 0x11. The type for“total_number_of_valves” property may be specified as a 16-bit signedinteger (e.g., SHORT)

TABLE 1 Example of a collection of PROPERTY-TYPE records PROPERTY NAMEPROPERTY ID TYPE WIDTH Pressure_in_tank_1 0x00000010 FLOAT 4total_number_of_valves 0x00000011 SHORT 2

Each of the PAMS property-type pairs may be listed or tabulated in aschema that may be referred to as a PAMS Application Descriptor Sheet(ADS). The schema may be encoded using the extensible Markup Language(XML). The complete tabulation of all property-type pairs may becontained in the PAMS ADS. The PAMS ADS may be a dictionary that containthe complete list of Property-Type records. The Node may store physicalmemory addresses of variables associated with the property data. ThePAMS ADS may facilitate establishing communications between the HSG 106and Nodes 110 and exposing the Node interface as a Web API via the Nodes110.

The PAMS ADS may also contain the metadata information for the Node 110.The PAMS ADS may also contain other information such as UNITS expressedas strings, property grouping information, and access rights informationfor the properties. The PAMS ADS may be stored in non-volatile memory ofthe Node 110 for later transfer to the HSG 106. In some configurations,the PAMS ADS may be separately communicated to HSG 106 by the developer.The Node 110 may parse the PAMS ADS to create a database of dataelements that are accessible via the communication interface.

The connectivity system 100 may include many Nodes 110. Each of theNodes 110 may be uniquely identified. Each Node 110 may be bound to a128-bit number that is referred to as a Universally Unique Identifier(UUID). The UUID may be used to uniquely identify each of the Nodes 110.The composition of the UUID may be as described in Table 2. The UUID mayinclude a Vendor ID (VID), a Solution ID (SID), a Software or FirmwareVersion (Version), and a Node Instance ID (NIID).

TABLE 2 Example composition of a NODE UUID FIELD WIDTH, (octets)Description VID 4 Vendor ID SID 4 Solutions ID Version 2 Software orFirmware version NIID 6 Node Instance ID

The UUID may serve two purposes. The first purpose may be to allow aunique identification for any Node 110 to the HSG 106. The secondpurpose may be to allow for the extraction of a PAMS ADS schema ID. Theschema ID may be used by the HSG 106 to retrieve the proper schemawithin the corresponding ADS repository. This allows the HSG 106 toautomatically establish communications with the node. The schema ID maycontain the VID, SID and Version fields of the UUID. At least one of theidentifiers may change when the data interface defined by the PAMS ADShas changed. The change in identifier may prompt the HSG 106 to requesttransfer of the updated PAMS ADS metadata.

The ADS for a Node 110 may be stored in a secure storage location thatis accessible by a qualified HSG 106. The HSG 106 may use the schema ID,that is derived from the Node UUID, to retrieve the Node ADS from thesecure storage location. For example, the secure storage location may beindexed by the Node UUID. The HSG 106 may store multiple ADS informationin the secure storage location for communication with a plurality ofNodes 110.

Message transactions may be structured such than none of the metadatadetails for any data transaction are exposed during a messaging session.The Node ADS may be configured to never expose any of its metadatadetails. The ordering of the PROPERTY/DATA transaction may be ad hoc andmay vary via the requests generated by the HSG 106.

The lack of visibility of the Node ADS along with the ad hoc nature ofeach messaging transaction creates an inherently secure system. Thefollowing demonstrates this via a discussion a typical GET or SETtransaction for HSG/Node transactions.

The ADS may contain all the information necessary to allow the HSG 106to perform a GET or a SET operation with the Node 110. The propertyidentifier values (PID_x), in the following examples may be defined aspredetermined 32-bit signed integers.

The example includes adding another PROPERTY to the example shown inTable 1. The new property incorporates a custom TYPE. The new propertyis labeled as “node_location”. Table 3 shows the updates metadata table.

TABLE 3 HSG/Node transaction example metadata PROPERTY NAME ID TYPEWIDTH Pressure_in_tank_1 PID_1 FLOAT 4 total_number_of_valves PID_2SHORT 2 node_location PID_3 GPS_COORD 16

Table 3 describes a new type specification for the “node_location”property. The new type is specified as the “GPS_COORD” type. Table 4shows the “GPS_COORD” type as a set of primitive types. The primitivetypes may be DOUBLE or IEEE 64-bit floating point numbers.

TABLE 4 Specification of the GPS_COORD type for the example PS_COORDNAME TYPE WIDTH “LATITUDE” DOUBLE 8 “LONGITUDE” DOUBLE 8

A GET REQUEST query by the HSG 106 to the Node 110 may involve sendingthe number of properties plus each of the PROPERTY IDs (PID-x). The Node110 may respond by echoing the number of properties requested along witheach PROPERTY ID followed by a list of data values.

FIG. 2 shows a possible message structure for the HSG 106 to Node 110GET request transaction. FIG. 2 depicts the inherent ad hoc nature ofthe data request. None of the metadata structure is visible. The “hidingof information” and the ad hoc nature makes the messaging transactionsinherently secure. FIG. 2 depicts a GET request transaction 200. The GETrequest may be a message transaction in which the HSG 106 requests datavalues from one of the Nodes 110. The GET request data 204 may bepopulated by the HSG 106 and sent to a Node 110. A GET request byteposition index 202 may depict the byte-positions of each element of theGET request data 204. The N_PROP field may represent the number ofproperties being requested. The PID_1, PID_2, and PID_3 fields of theGET request data 204 may represent the PROPERTY_IDs that are beingrequested. Note that the number of PROPERTY_IDs should match the valuestated in the N_PROP field. In the example, fourteen message bytes areutilized for the GET request data 204. Note that if additionalPROPERTY_IDs are requested, the number of message bytes needed for theGET request data 204 will be increased.

FIG. 2 also depicts the GET response data from the Node 110. The GETresponse data may include a first set 206 of message bytes, a second set208 of message bytes, and a third set 210 of message bytes. In theexample, the sets of message bytes may be up to 16 bytes or octets inlength. Each of the message bytes may be indexed by the byte positionindex 202. In addition to repeating the requested PROPERTY_IDs, the Node110 may send the corresponding value of the PROPERTY_IDs. For example,VAL_3 represents the value of PID_3 and consumes sixteen bytes of themessage. VAL_1 represents the value of PID_1 and consumes four bytes ofthe message. VAL_2 represents the value of PID_2 and consumes two bytesof the message. The number of bytes consumed by the values shouldcorrespond to the WIDTH for each of the PROPERTY_IDs. Some of the valuesmay be represented by bytes in more than one of the sets. For example,VAL_1 includes data in the second set 208 and the third set 210 ofbytes. In response to receiving the GET request, the Node 110 may beprogrammed to read the associated values of the requested PROPERTY_IDs.The Node 110 may search the ADS to determine the variable instancesassociated with the requested PROPERTY_IDs. The node 110 may read thevalue from the corresponding memory location and populate the responsemessage.

Since HSG 106 and the Node 110 have access to the ADS information, thecontents of the message can be easily decoded. The HSG 106 or Node 110may search the ADS for the properties associated with the PID_x valuesthat are included in the message. The associated property-type canindicate the message space consumed by each of the values correspondingto the PID_x values. This allows the Node 110 to populate the message ina consistent manner that is recognizable by the HSG 106.

Based on this interface, the HSG 106 can easily request data values forany PROPERTY_IDs that are defined in the PAMS ADS. Further, the PAMS ADSprovides information as to the data length and format that will bereturned by the Node 110. The HSG 106 can reference the PAMS ADS todecode the received message.

FIG. 3 shows a possible message structure for the HSG 106 to Node 110SET request transaction. The Node 110 may respond with the list ofproperty IDs to confirm the SET request message. FIG. 3 depicts a SETrequest transaction 300 that is designed to allow the HSG 106 to providedata values to the Nodes 110. The HSG 106 may populate data fields inthe SET request message. The SET request data may include first group304, a second group 306, and a third group 308 of data bytes. The groupsmay be indexed by a byte position index 302. The N_PROP field representsthe number of properties being set. The PID_3, PID_2, and PID_1 fieldsrepresent the PROPERTY_IDs for which values are being provided. TheVAL_3, VAL_1, and VAL_2 fields represent the data values for thecorresponding PROPERTY_IDs.

FIG. 3 also depicts the SET response data from the Node 110. A SETresponse message 310 may include the PROPERTY_IDs that were received inthe SET request from the HSG 106 and be indexed by the byte position302. The SET response message 310 may confirm the successful receipt andprocessing of the SET request.

The GET and SET message transfers allow data to be transferred betweenthe HSG 106 and Nodes 110. The GET request allows the HSG 106 toretrieve data from the Nodes 110. For example, the Nodes 110 may includeprocess monitoring variables such as pressures or temperatures. The SETrequest allows the HSG 106 to set values that may control operation ofthe Nodes 110. For example, the SET request may be used to providevalues for process control features such as a pressure setpoint or atemperature setpoint. The SET request may be used to activate ordeactivate process operations. The actual type of variables that may beoperated on by the GET and SET requests may be those exposed in the PAMSADS. This allows Node developers to expose only those variables thatshould be exposed. For example, only variables defined in the ADS can besubject to a SET request. The visibility of variables in the Nodes 110is defined and controlled by the Node developer. For example, the ADSmay include a read only control bit associated with each PROPERTY_ID toprevent SET requests on certain PROPERTY_IDs.

In order to establish the management interface, the HSG 106 must obtaina valid ADS from the Node 110. The HSG 106 may accomplish this via anHSG/NODE ADS transaction method.

There may be two methods defined for establishing the messagingconnection between the HSG 106 and Node 110. The two methods may bereferred to as a PUSH connection and a PULL connection. The PULLconnection method may be used when the HSG 106 and the Node 110 areco-located. In the PULL connection method, the HSG 106 may query theNode 110 and the connection may be established responsive to the Node110 acknowledging the query.

The PUSH connection method may be used when the HSG 106 resides at anexternal site or on the Internet Cloud. The Node 110 may be locatedbehind a corporate firewall. The connection establishment may beinitiated by the Node 110. The Node 110 may send a query for a valid HSG106 and the connection may be established responsive to the HSG 106acknowledging the query.

In either the PULL connection or the PUSH connection, the query may bepart of the MIMS transport protocol.

The HSG 106 may retrieve the Node ADS in order to establish a datatransaction session. FIG. 4 shows the flowchart 400 for a possiblesequence of operations for establishing an ADS transaction session. Atoperation 402, a connection may be established between the HSG 106 andthe Node 110. The connection may be established by either the PUSHconnection method or the PULL connection method. Upon establishing theconnection, operation 404 may be performed. At operation 404, the HSG106 may query the Node 110 for the UUID associated with the Node 110.

At operation 406, the HSG 106 may parse a Schema ID from the UUID thatis received from the Node 110. At operation 408, the HSG 106 may searchan associated storage area to locate the corresponding ADS using theSchema ID. For example, the HSG 106 may maintain a database thatincludes the ADS for each of the Nodes 110 that it has established aconnection to. The database may be indexed by the Schema ID. If nocorresponding ADS is found, operation 412 may be performed. At operation412, the HSG 106 may use a default ADS to establish communication withthe Node 110. The default ADS may contain a list of commonly supportedproperty-type entries. The HSG 106 may query the Node 110 for thecorresponding ADS. If the corresponding ADS is found, operation 410 maybe performed. At operation 410, the HSG 106 may parse the ADS and builda property/type database.

At operation 414, the application server 104 may render the databaseentries as a Web API and expose the Web API for use by other devices orapplications. The application may be an ERP application that is executedon a web-connected device. At operation 416, the HSG 106 may manage theNode 110. The Node management information may be exposed as a Web API.The Web API may provide an interface for web servers and/or webbrowsers. The Web API may be used by applications connected to theconnectivity system 100 for accessing information from the Nodes 110.The HSG 106 may respond to requests from the Nodes 110 and applicationserver 104 according to the ADS. For example, the ADS may define processvariables that are accessible.

The ADS dictionary may be manually generated by the systems architect.The ADS may then be implemented by the Node software developer. The ADSdictionary may be stored in memory of the Node 110 for later retrieval.The manual process may be cumbersome and prone to errors inimplementation.

A method for marking up the Node software code or firmware based on thesystem requirements is presented. Advantages of marking up the codeincludes a less error-prone implementation, better diversity andaccuracy of results by usage of tools used by source-level debuggingsystems, and “imprinting” of the code by the developer. This “imprint”is the PAMS ADS markup method.

The PAMS ADS markup technology may be implemented by the “enumeratedtype” construct that is included in many programming languages. Theenumerated type may be a typing construct that binds a label (e.g., astring) to a fixed constant. Both the label and constant are thenavailable in the build and run-time environments.

The enumerated type, which is a label bound to an integer constant, maybe used as an alias for the PROPERTY. As presented earlier with respectto Property-Type Pairs, the PROPERTY may consist of a PROPERTY NAME anda PROPERTY ID. There are similarities between the characteristics of thePROPERTY and the Enumerated Type construct. A list of PROPERTIES may beexpressed as a simple list of enumerated types. This construction may beapplicable to most modern languages such as C, C++, JAVA, C#. The PAMSADS markup method may be implemented by exposing the list of PROPERTIESas a set of enumerated types.

The markup rules for the PAMS ADS markup may applied to the software foreach individual Node 110. The rules may define how each PROPERTY isbound to an instance of a variable. The instance refers to a variablewithin the application code that is represented by a number.

Management of the PROPERTY-TYPEs may be guided by various rules. A Nodemay be managed by a list of PROPERTY-TYPE pairs. A PROPERTY may consistof a PROPERTY NAME and a PROPERTY ID. A PROPERTY may be bound to asingle variable instance. The data of the variable instance may bemanifested as a VALUE. The structure of the VALUE may be the data type.The instance name may be rendered using the PROPERTY NAME. Each PROPERTYand fields associated with the PROPERTY may be unique for the Node 110.

Any number of Enumerated Types may be specified by creating the list ofPROPERTY NAMES and PROPERTY IDS. Each PROPERTY may be part of anEnumerated Type list. The primary constraint may be that each NAME andeach ID are unique within the Node context. The following is an exampleprocess that may be used for the code markup. A first step may be todefine and declare each Enumerated Type list. A second step may be toensure that each PROPERTY NAME and PROPERTY ID is unique. A third stepmay be to add each PROPERTY as a PROPERTY NAME to a single EnumeratedType list. A fourth step may be to bind the PROPERTY NAME to a variableinstance. A fifth step may be to ensure that the markup is syntacticallycorrect and that the code builds properly.

A string prefix may be added to a PROPERTY NAME to ensure the uniquenessof any PROPERTY NAME. Also, an integral value may be placed within theEnumerated Type to ensure the uniqueness of any PROPERTY ID. To avoidnamespace contentions, a string prefix may be added to a variableinstance.

A tag prefix for the PROPERTY NAME may be referred to as the propertyname prefix, “<pnpfix>”. The tag prefix may be pre-pended to thePROPERTY NAME. This ensures the uniqueness of the PROPERTY NAME withinthe code namespace.

The tag prefix for the variable instance may be referred to as thevariable name prefix, “<vnpfix>”. The variable name prefix may bepre-pended to a bound variable. The PROPERTY NAME for the variableallows the binding of the variable instance to a PROPERTY. The“<vnpfix>” prefix is used to ensure the uniqueness of the variable namewithin the code namespace. The tag prefixes may also provide a searchstring that may be used when parsing the variable definition files.

The following is an example using the C or C++ programming language.This example lists three properties as previously described by Table 3and Table 4. The definition and declaration of the enumerated types inthe C programming language is depicted in Table 5 and Table 6. In thisexample, two enumerated types are declared. The enumerated types arelabeled as propertyMaster_common (see Table 5) andpropertyMaster_application (see Table 6). The ellipsis represents aplaceholder for the list of properties. The propertyMaster_commonenumerated type may be used for Properties that are common to all Nodes.The propertyMaster_application enumerated type may be used forapplication specific properties. In the example presented, the“<pnpfix>” tag is defined as “_PROP_”.

TABLE 5 Example of Enumerated Type for a set of COMMON PROPERTIES.typedef enum propertyMaster_common { _PROP_node_location = 0, ...propertyMaster_common_END } propertyMaster_common;

TABLE 6 Example of Enumerated Type for list of application specificPROPERTIES typedef enum propertyMaster_application {_PROP_Pressure_in_tank_1 = 0x800, _PROP_total_number_of_valves, ...propertyMaster_application_END } propertyMaster_application;

The ending entry, (“propertyMaster_common_END”), may be the endingplaceholder for the common property enumeration list.

Table 5 shows an offset of 0 for the common properties. Table 6 shows anoffset of 0x800 for the application specific properties. This implies ablock of PROPERTY IDs of 0x0000 to 0x7FF for all common properties. Theapplication specific PROPERTY IDs may have values greater than or equalto 0x800. In the example shown, the property Pressure_in_tank_1 has aPROPERTY_ID of 0x800 and the property total_number_of_valves has aPROPERTY_ID of 0x801. Additional properties will have an incrementedPROPERTY_ID.

The following description describes how to bind an instance of avariable to a PROPERTY. The PROPERTY NAME may be used as part of thelabel for the variable. Table 7 shows how a variable may be defined forthe “node_location” property.

Table 7 introduces a user-defined type “GPS_COORD”. The record defines astructure that contains two double precision numbers. The total storagerequirements for the “GPS_COORD” type may be 16 octets.

TABLE 7 Example of binding a variable instance to a PROPERTY typedefstruct GPS_COORD { double LATITUDE: double LONGITUDE; } GPS_COORD;GPS_COORD_xmlvar_node_location;

The example defines the “<vnpfix>” tag for the variable prefix. The“<vnpfix>” tag may be defined as the string “_xmlvar_”. Using the tagassures the uniqueness of the “_xmlvar_node_location” for the“node_location” within the code namespace. The variable may be used inthe software. During run-time, a value may be written to the variable byoperation of the software.

Table 8 shows an example of instance variable binding for the“Pressure_in_tank_1” and the “total_number_of_valves” properties. Inthis case, the bindings are simple global declarations. Also shown is aglobal “ANSI-C” initialization used for the “total_number_of_valves”property. Global initializers, ANSI modifiers, (e.g., const, volatileand static) may be allowed. The ADS scanner tool may allow for alllegitimate “C” or “C++” constructs and descriptors.

TABLE 8 Example of binding variables to PROPERTIES using C types. float _xmlvar_Pressure_in_tank_1; short  _xmlvar_total_number_of_valves = 31;

The process of generating the ADS may be automated. A program may bewritten that scans the program files to locate the defined PROPERTIES.The ADS dictionary generation may be described by an ADS generationflowchart 500 as depicted in FIG. 5. At operation 502, the system maysearch for defined enumerated types. For example, the system may searchfor the string for enumerated types that are defined in the software. Inthe C example, the system may search for the properytMaster_common andpropertyMaster_application enumerated types.

At operation 504, the enumerated type is found. The system maytemporarily store the associated enumerated type information for furtherparsing. For example, the search may yield the enumerated type ofpropertyMaster_common as defined in Table 5. At operation 506, thesystem may acquire the PROPERTY_NAME and PROPERTY_ID information. Forexample, the system may parse the enumerated type structure for theproperty name prefix, “<pnpfix>”. The PROPERTY_NAME may be parsed as theportion of the string following the property name prefix. ThePROPERTY_ID may be defined as the associated value. Continuing theexample, the PROPERTY_NAME of “node_location” may be found with aPROPERTY_ID of zero.

At operation 508, the system may search for variable instances. Thesystem may parse the files searching for the variable name prefix,“<vnpfix>”. Further, the system may further search for a stringfollowing the variable name prefix that matches the PROPERTY_NAME.

At operation 510, the variable instance may be found. Continuing theexample, the node_location as defined in Table 7 may be recognized. Thesystem may temporarily store the associated variable information forfurther parsing. At operation 512, the system may acquire typeinformation for the PROPERTY. In the example, the system may search fortype information defined as GPS_COORD.

At operation 514, the property type information may be stored in the ADSdictionary. For example, the ADS dictionary may be maintained as an XMLfile.

At operation 516, the system may check if all properties have beenfound. If there are more properties to be found, operations 506 through516 may be repeated. All properties may have been found if there are nomore elements to parse in the enumerated type structure. If allproperties have been found, operation 518 is performed.

At operation 518, the ADS dictionary is generated. Additional processingmay be performed to complete the ADS dictionary. For example, additionalXML template information may be added to the file. In someimplementations, the generation of the ADS may be automated as asoftware program that parses the Node software files and generates theADS.

Other languages, (e.g., C# and JAVA) may have metadata facilities builtin. In these cases, the XML scanning facility may be partially suppliedby the toolchain. However, the PROPERTY-TYPE binding may still berequired for these cases.

In the C# case, the metadata may be marked by inheriting the Attributeclass. In this case, each variable instance may be derived from theAttribute class. The PROPERTY NAME, PROPERTY ID pair may still be boundto the variable instance. The scanning and exposing of the metadatainformation may be done by the toolchain.

In the JAVA case, the metadata may be marked by using JAVA annotation.In this case, the JAVA annotation may be used to expose the metadata foran instance variable. As in the C and C++ examples, the PROPERTY-TYPEbinding may be affected via a property list search and qualifying thePROPERTY NAME with an exposed variable instance.

FIG. 6 shows a possible markup workflow 600 for generating the ADSdictionary. At workflow 602, source code may be developed for the Node.The developer may create the project and write the firmware for theproject. The source code may be constructed based on systemrequirements. The system requirements may define variables that are tobe exposed via the ADS dictionary. Variables that are to be exposed maybe defined and declared as described previously herein. The developermay mark up the code to expose the PROPERTIES/INSTANCES/TYPEinformation.

At workflow 604, the source code may be compiled and linked. Thecompilation process involves converting the individual source code filesinto machine executable code. The result may be multiple object files.The linking process involves combining the object files into a singleexecutable image. During linking, addresses are assigned to program codeand variables (e.g., process variables). An additional output of thelinking process may be a symbol table. The symbol table may be a list ofprogram routines and variable names with address locations. The outputof the linking process may be an executable image 606 that includessymbol information.

At workflow 608, the symbol table may be scanned and parsed for ADSdictionary information. The output may be the ADS dictionary 610. Inaddition, XML annotations 612 may be created by the developers. Atworkflow 614, an XML annotator tool may combine the ADS dictionary 610and the XML annotations 612 into an annotated ADS 616. The XML annotatortool may include compression and encryption features to reduce file sizeand improve security. The annotated ADS 616 may be released along withthe executable image 606.

The annotated ADS 616 may be stored in non-volatile memory of the Node110. In this manner, the annotated ADS 616 may be available to any HSG106 that is in communication with the Node 110. Information from theannotated ADS 616 may be transferred to the HSG 106 and the exchange ofdata between the HSG 106 and the Node 110 may be guided by the ADS. Forexample, selected metadata regarding the data interface of the Node 110may be transferred to the HSG 106.

FIGS. 7A and 7B shows a possible connectivity topology 700 of a typicalcluster of networking and communications systems. The Media IndependentMessaging Service (MIMS) session layer may be implemented as thecommunications method between the HSG 106 and the Nodes 110. Also shownare the MIMS enabled local connections between USB terminals 706, 722and the Nodes 110. The MIMS may be layered over the existingcommunication protocol between the HSG 106 and the Nodes 110. The Nodes110 may communicate with local devices via independent native protocolsthat are independent of the MIMS.

The connectivity topology 700 may include a first local domain 702. Ingeneral, a local domain may be defined as a node that communicates withone or more local devices. The first local domain 702 may include afirst node 704 that communicates with a first set of local devices 708.Communication within the first local domain 702 may be via an RS485communication link. The first node 704 may communicate with the firstset of local devices 708 over the RS485 communication link using apredetermined protocol. The predetermined protocol may be a standard orproprietary communication protocol. The first node 704 may communicatewith the HSG 106 via an Ethernet communication link using the MIMSsession layer. A first USB terminal 706 may communicate with the firstnode 704 via a USB communication link and a MIMS session layer.

The connectivity topology 700 may include a second local domain 712. Thesecond local domain 712 may include a second node 714 that is incommunication with a second set of local devices 716. The second node714 and the second set of local devices 716 may communicate over a fiberoptic communication link. The first node 704 may communicate with thesecond node 714 over a fiber-optic communication channel 710 using aMIMS session layer.

The connectivity topology 700 may include a third local domain 718. Thethird local domain 718 may include a third node 720 that is incommunication with a third set of local devices 724. The third node 720and the third set of local devices 724 may communicate over a wirelessEthernet channel (e.g., Wi-Fi). The third node 720 may communicate withthe second node 714 via an Ethernet connection using the MIMS sessionlayer. A second USB terminal 722 may communicate with the third node 720via a USB communication link and a MIMS session layer.

FIG. 8 provides alternative representation 800 of the connectivitytopology 700 further describing the interconnection of the localdomains. Each of the first node 704, the second node 714, and the thirdnode 720 may be a coordinator/controller for a specific Local Domain.Each of the Local Domains (LD) may have some common characteristics.MIMS may be implemented as a session layer on the Local Domain. MIMS mayalso be implemented as the data link layer for the Local Domain. The LDnodes may be a single MASTER with multiple SLAVE connections. Each MIMSLD may support a specific fixed size data frame transfer. Some LD nodesmay support a multiple LD routing capability.

FIG. 8 also depicts that nodes and devices may operate in a Master (M)or Slave (S) mode. The nodes and devices may also operate as both aMaster and a Slave (M/S). The HSG 106 may operate as a Master. The firstnode 704 may operate as a Master/Slave. The first USB terminal 706 andthe second USB terminal 722 may operate as Master nodes. The second node714 and the third node 720 may operate as Master/Slave nodes.

A Web Services Terminal 802 may be in communication with the ApplicationServer 104. The Application Server 104 may also be in communication withERP Services 804. The ERP Services or ERP Applications may be one ormore applications that are executed on an external device or terminal.The ERP Application may include or be associated with a user interfacethat allows a user to access various features. For example, the ERPApplication may permit read and/or write access to process variablesthat are defined in the Nodes.

It is desired to maintain all existing protocols for any local domain.The system may allow a seamless transport management of control andstatus variables in a protocol-independent fashion. Features of the MIMSsession layer may allow forwarding to any node to communicate to anothermaster/slave node. Each of the SLAVE nodes may acknowledge any MASTERnode requests. All CONTROL fields may be in network byte order (BIGENDIAN). PAYLOAD fields may be either BIG ENDIAN or LITTLE ENDIAN order.The frame length may be fixed and dependent on the characteristics ofthe associated Local Domain. Frames may be automatically aggregated tomaximize media bandwidth utilization. The MIMS session layer may allowfor multi-frame block transfer of data.

FIG. 9 shows a possible layout 900 of a MIMS frame. Each frame may befixed in length. The length of the frame may be dependent on thecharacteristics of the LOCAL DOMAIN. Individual octets within the framesmay be indexed by a hexadecimal octet position index 902 and/or adecimal octet position index 904. Octets with the MIMS frame may also beindexed by a hexadecimal address 906 and/or a decimal address 908. Forexample, the position within the MIMS frame of any byte of informationmay be determined by using the hexadecimal octet position index 902 andthe hexadecimal address 906.

The maximum allowable frame size of a MIMS frame may be 1056 octets. Theminimum MIMS frame size is 128 octets. The frame size for any MIMS framemay be fixed by the constraints of the local domain.

The MIMS frames may include some common fields. Each MIMS frame mayinclude a 32-octet header and a payload section. The payload sectionencapsulates the data. There may be six fields that are common for allMIMS frames. The common fields for any MIMS frame may be summarized inTable 9.

TABLE 9 MIMS header common fields Field Offset Size (octets) DescriptionSY 0 2 SYNC = unique agreed upon 2- octet number CRC32 2 4 32-bit CRCPTYPE 6 2 Protocol type and payload size MFC 8 2 Media Frame Controlbyte CSW 10 2 Control and status word FTAG 12 2 Frame TAG identifier

A Frame SYNC (SY) field may be a two-octet sync field that is includedat the start of the frame. The values for this field may be some uniqueagreed-upon two-octet number. This field may indicate the start of theMIMS frame. A Frame Check (CRC32) field may following the SY-field andmay be a four octet CRC32 field. The CRC32 may be calculated from theoctets starting at offset 0x06 to the end-of-frame octet inclusive. Thepolynomial used for the CRC32 calculation may be 0x04C11DB7.

A Protocol Type (PTYPE) field may be a two-octet field that signifiesthe protocol and the payload size. FIG. 10 shows a map 1000 of a PTYPEbit-field definition 1004 as indexed by a bit position index 1002. ThePTYPE field may remain un-altered during any forwarding, aggregation orblock transfer processes. The PTYPE field may include a three-bit SIZEfield and a thirteen-bit PROTOCOL field.

The SIZE field may indicate a Local Domain MEDIA FRAME size. There maybe four SIZE values supported by the protocol. The payload sizes may beas shown in Table 10.

TABLE 10 PTYPE.SIZE bit field definitions PAYLOAD SIZE OCTETS Type 0reserved reserved 1 96 MIMS_128 2 224 MIMS_256 3 512 MIMS_544 4 1024MIMS_1056 5 . . . 7 reserved reserved

The PROTOCOL field may have allowed values as shown in Table 11. Theprotocol type allows for a wide variety of addressing modes and varioustypes of parsing rules for a frame. A full description of each protocolis described herein. Protocol types with values less than 0x7FF may bereserved for all protocols supporting MIMS addressing. Protocol typeswith values within the range (0x800 . . . 0xCFF) may be set aside forany vendor or user specific cases. There may be two common PROTOCOLtypes defined. The common protocol types may be defined as theCAPABILITY and PROPERTY types. Both of the common protocols aredescribed herein.

TABLE 11 COMMON MIMS addressing protocols VALUE PROTOCOL AddressDescription 0x0000 CAPABILITY MIMS Capability description protocol0x0001 PROPERTY MIMS GET/SET property-value pair using MIMS addressing

Referring again to FIG. 9, a media frame control (MFC) field may bedefined that allows devices to transport frames using the most efficientmedia/bandwidth utilization. FIG. 11 shows a map 1100 of a MFC bit-fielddefinitions 1104 as indexed by a bit position index 1102. The MFC field1104 may define a five-bit field for a Multi-Frame Size (MFS) field thatmay be a non-zero value for a multi-frame transfer. The MFC field 1104may define a five-bit field for a Multi-Frame Index (MFI). Theoperational aspects of the MFC 1104 field are described herein.

A control and status word (CSW) field may be defined that enables theMASTER to send control information to the SLAVE. For a MASTER to SLAVEtransfer, the CSW field may represent a control word. For a SLAVE toMASTER transfer, the CSW field may represent a status word. The CSWfield may also be used as part of a BLOCK transfer mechanism for theprotocol. The CSW field may be divided into a set of bit fields. Thedefinitions of the bit fields for the MASTER to SLAVE transaction may beas shown in FIG. 12. FIG. 12 shows a map 1200 of a CSW bit-field 1204 asindexed by a bit position index 1202.

The CSW bit-field 1204 may define a control/protocol direction bit (CTL)The CTL bit may allow a MASTER to send a GET or SET request to a SLAVEdevice. Table 12 shows the possible definitions for the CTL for MASTERto SLAVE transactions. For example, the CTL bit being set to zero mayindicate that the MASTER is requesting a GET transaction from SLAVE. TheCTL bit being set to one may indicate that the MASTER is requesting aSET transaction to the SLAVE.

TABLE 12 MASTER to SLAVE CTL bit definitions CTL Description 0 MASTERrequests a GET transaction from the SLAVE 1 MASTER requests a SETtransaction to the SLAVE

The CSW bit-field 1204 may define a block transfer size/enable (BLK)field. Multi-frame block transfers may be supported by all protocoltypes. The rationale for doing this may be to allow for more efficienttransfers of larger blocks of data. Instead of requiring the SLAVE toacknowledge each individual MASTER request, the multi-frame blocktransfer requires the SLAVE to acknowledge a set of frames for a singleblock transfer. The BLK field may have a length of four bits.

The MASTER may send a block transfer request via the BLK field. A BLKfield value of zero may indicate a normal frame transfer with a singleSLAVE acknowledge. A BLK field with a non-zero value may indicate ablock transfer and a frames-per-block request. Table Table 13 shows apossible definition for the BLK field for a MASTER to SLAVE blocktransfer request. A non-zero value may be indicative of a number offrames per block.

TABLE 13 MASTER to SLAVE BLK block transfer request definitions BLK NDescription 0 0 Block transfer mode disabled, normal frame transfer 1 .. . 15 2 . . . 16 N = FRAMES PER BLOCK = (BLK + 1)

The CSW-bit field 1204 may define a MIMS Addressing Mode (MAM) field.The MAM field may only apply to PROTOCOL types represented by a valueless than 0x800. There may be two types of MIMS addressing available.The two modes may include static addressing and dynamic addressing. Avalue of zero may select the static MIMS addressing mode. A value of onemay select the dynamic MIMS addressing mode.

The static addressing mode may use a 6-octet MIMS address that isstatically assigned. The resolution of the MIMS address may bedetermined via a local domain address resolution or set of rules.

The dynamic addressing mode may use a 6-octet MIMS address that isassigned to a SLAVE by the local domain MASTER. In this case, the upperthree octets may be statically assigned by the MASTER. The MASTER mayrandomly generate the lower three octets and combine them to form thefull six-octet MIMS address. The assignment of the dynamic address maybe done in such a way to assure that there is no address contentionwithin the local domain.

There may be a case where an upstream MASTER detects a MIMS addressconflict within the entire network. In this case, the upstream MASTERcan signal to the local domain MASTER to reassign the SLAVE MIMSaddress.

The definitions of the bit fields for the SLAVE to MASTER transactionmay be as shown in FIG. 13. FIG. 13 shows a map 1200 of a Statusbit-field 1304 as indexed by a bit position index 1302. SLAVE to MASTERstatus and acknowledgement may be affected via the control and statusCSW field.

In this mode, the CSW-field may define a SLAVE status field (SSTAT). TheSLAVE status field may be a PROTOCOL type status field. A zero in thisfield may indicate that the transaction was processed with no errors. Anon-zero value in this field may indicate that an error has occurredduring the processing of the transaction.

The SLAVE to MASTER CSW-field may include a MIMS Addressing Mode (MAM)field. The definition for this field may be the same as describedpreviously for the MASTER to SLAVE transaction. In this direction, theSLAVE may return the proper setting for the MAM bit as assigned by thelocal domain MASTER.

The CSW-field may define a SLAVE EVENT notification signal (E). For aresponse to a MASTER to SLAVE message, the E field may be set to zero.If capable, a SLAVE may generate an unsolicited message or event. In thesituation where the SLAVE cannot generate an asynchronous message, theSLAVE must wait for the MASTER to query. At this point the SLAVE maysubstitute an event frame for the response. The connectivity system maydefine a set of rules for event or unsolicited messages. For example,any SLAVE may send an event message to the MASTER within the localdomain. An EVENT or unsolicited message may be marked by setting theE-field to one. An EVENT message may always a single MEDIA FRAME. TheMASTER may not acknowledge any received event message. A MASTER mayreceive the message and may forward the message to all MASTERS in theupstream direction. A SLAVE event frame may always be sent as a singleMEDIA FRAME.

The CSW-field may define a control transfer error status (CERR) field.The control transfers error status may be signaled via the CERR field.The CERR field may signal an error with the header or a controltransaction. A zero value may indicate a successful control transferresponse. A non-zero value may indicate an unsuccessful control transferresponse.

The CSW-field may define a data transfer error status (DERR) field. Thedata transfer status may be signaled via the DERR field. The DERR fieldmay signal an error within the payload. The protocol application layermay control the operation of the DERR field. A zero value may indicate asuccessful data transfer response. A non-zero value may indicate anunsuccessful frame transfer response.

The CSW-field may define a SLAVE block transfer size (BLK) field. TheSLAVE to MASTER BLK field may be filled with the original block transferblock size as requested by the MASTER. The bit field definitions may bethe same as shown in Table 13.

The CSW-field may define a SLAVE get/set response indication (CTL)field. The CTL bit-field may indicate a GET or SET response. A possibledefinition for this bit field is shown in Table 14.

TABLE 14 SLAVE to MASTER CTL Control bit field response CSW.CTLDescription 0 SLAVE GET response 1 SLAVE SET response

Referring again to FIG. 9, a frame tag (FTAG) field may be defined. TheFTAG field may identify a frame sent from the MASTER. The FTAG field maydefine two different formats depending on whether the frame is part of aBLOCK transfer or a single frame transfer. Rules for setting the FTAGfield may be defined. For example, The FTAG may be a frame sequenceidentifier. The FTAG may be a frame sequence number when the BLK is setto zero. FTAG may contain a block ID (BID) bit-field and frame count(FC) bit-field for block transfers (e.g., BLK≠0). FIG. 14 depicts a map1400 of a FTAG bit field 1404 indexed by a bit position index 1402 whenthe BLK value is zero. FIG. 14 also depicts the FTAG bit field 1404indexed by bit position 1402 when the BLK value is non-zero thatconsists of a BID field and a FC field.

The connectivity system may define how frame transfers are to occur.MIMS frames may be fixed in length. There may be two types of framesused within the MIMS architecture. There is the actual frame that istransported on the media. This frame may be referred to as the MEDIAFRAME.

There may be a frame that may or may not be the same size as the MEDIAFRAME. These frames contain all control information within the headerwhich allows for routing and block transfers. This frame may be referredto as the PROTOCOL FRAME. The MEDIA FRAME may transport the PROTOCOLFRAME. The PROTOCOL FRAME may carry the information that is parsed bythe SLAVE nodes.

Each local domain type may be specified to support a fixed number ofoctets for a transfer. The frame that is transported by the nodephysical layer (PHY) may be the MEDIA FRAME. The MEDIA FRAME may followcertain rules. The node physical layer transports information packagedinto a MEDIA FRAME. The MEDIA FRAME length may be set by the transportconstraints of the Local Domain or MEDIA. The MEDIA FRAME uses the MIMSformat. All CRC32 values may be calculated and stamped onto a MEDIAFRAME.

The PROTOCOL FRAME size, in addition to the constraints of the MEDIA andthe MFC field are used to moderate all frame transfers. The PROTOCOLFRAME size may be set by the originating MASTER. The MFC field may bemodified by the MASTER device. FIG. 11 shows the layout of the MFCfield. The MFC field may define two bit-fields. The bit-fields aresummarized in Table 15.

TABLE 15 Bit-field summary for the Media Frame Control (MFC) fieldBit-field Name Description, (summary) MFS MEDIA frame Count Total numberof frames for a MEDIA FRAME transfer MFI MEDIA frame Index MEDIA FRAMEtransfer index

Only MASTER devices may be allowed to modify the MFC field. Any targetedSLAVE device will echo this field. The MEDIA FRAME transfer index (MFI)may be used to keep track of the currently transmitted MEDIA FRAME. TheMFC field may adhere to certain rules. Only routing capable devices maybe allowed to modify the MFC field. The transfer may be split intomultiple transfers if the PROTOCOL FRAME size is greater than the MEDIAFRAME size. Only MASTERS may be allowed to split a PROTOCOL FRAME intomultiple MEDIA FRAMES. A PROTOCOL FRAME with length not equal to theMEDIA FRAME may be encapsulated. A PROTOCOL FRAME with length equal tothe MEDIA FRAME is not encapsulated.

The MEDIA FRAME transfer Count MFS bit field represents the total numberof frames to transmit for a multi-frame transfer. A value of zeroindicates a single frame transfer.

In the multi-frame transfer; the total number of transferred MEDIAFRAMES is equal to a value of MFS+1. The equation for the total numberof transferred MEDIA FRAMES is represented as Equation (1). The entirePROTOCOL FRAME may be encapsulated by multiple transfers of the MEDIAFRAMES.

$\begin{matrix}{{M\; F\; S} = {{INT}\left( \frac{{PROTOCOL\_ FRAME}_{size}}{{MEDIA\_ FRAME}_{{payload}\mspace{14mu}{size}}} \right)}} & (1)\end{matrix}$where MFS is one less than the total number of MEDIA FRAMES totransport, PROTOCOL_FRAME_(size) is the entire protocol frame sizeincluding the header, and MEDIA_FRAME_(payloadSize) is the MEDIA FRAMEsize minus 32.

The MFI bit-field may be an index that tracks MEDIA FRAME transfers. Thefirst transmitted MEDIA FRAME may be indexed as zero. The MFI bit fieldmay be incremented for each subsequent MEDIA FRAME transfer. The MFI bitfield may be set to zero for a single MEDIA FRAME transfer.

The PROTOCOL FRAME may have any valid MIMS payload length. The lengthmay be set by the device's data link layer in the SIZE field. Thisallows any device to split or aggregate protocol frames into a set ofMEDIA FRAMES. This maximizes the efficiency of transport across severalLocal Domains. A PROTOCOL FRAME may follow several rules. PROTOCOL andMEDIA FRAMES for protocol types 0x0800≤protocol<0xFFFF are identical.The SIZE field may be set by the sourcing MASTER. A targeted SLAVEdevice may respond with the PTYPE.SIZE field as set by the sourcingMASTER.

Any generated PROTOCOL FRAME in which the frame length is equal to theMEDIA FRAME length is not encapsulated. In this case, the PROTOCOL FRAMEand the MEDIA FRAME are identical. The frame is transported as a singleframe transfer.

Any generated PROTOCOL FRAME in which the frame length is less than theMEDIA FRAME length will be issued as a single MEDIA FRAME transfer. ThePROTOCOL FRAME is completely encapsulated in the MEDIA FRAME payload.The small frame transfer may be subject to some rules. For example, thePROTOCOL FRAME, including the header, is completely encapsulated in theMEDIA FRAME payload. Any required excess octets may be padded toaccommodate a single MEDIA FRAME transfer.

The PROTOCOL FRAME may be split into multiple MEDIA FRAME transfers whenthe PROTOCOL FRAME length exceeds the MEDIA FRAME length. The totalnumber of MEDIA FRAME transfers may be split to an integral multiple ofthe number of MEDIA FRAMES required to transmit the entire PROTOCOLFRAME. The multi-frame transfer may be subject to some rules. Forexample, the entire PROTOCOL FRAME is fully encapsulated in the MEDIAFRAME payloads. The transfers are split into MFS+1 MEDIA frames as perthe MFS rules. Each MEDIA FRAME transfer may be indexed using the MFIbit-field. The receiving device shall re-assemble the MEDIA FRAMES intoa PROTOCOL FRAME using the MFC field information.

The following illustrate the frame transport rules via a set of usecases. In these sections, the set of scatter-gather rules areillustrated.

FIG. 15 shows a first use case 1500 in which the PROTOCOL FRAME lengthexactly matches the MEDIA FRAME length. The transfer and forwarding areboth single frame transfers where the frame control fields are setup bythe originating MASTER as shown in Table 16. In this case, the PROTOCOLFRAME and MEDIA FRAME are IDENTICAL.

TABLE 16 MASTER MFC field setup for PROTOCOL_FRAME length = MEDIA FRAMElength Field Value Comments PTYPE.SIZE 2 MIMS_256 MFC.MFS 0 Setup forsingle frame transfer MFC.MFI 0 Don't care

In this case, a MASTER Node 1504 may be configured to transmit with aPROTOCOL FRAME size of 256 octets (e.g., MIMS_256). The message may betransmitted to a M/S Node 1502 with a MEDIA FRAME length of 256 (e.g.,MEDIA_256). The M/S Node 1502 may transfer the message to a SLAVE Node1506 with a MEDIA FRAME length of 256 octets (e.g., MEDIA_256). TheSLAVE Node 1506 may send a response with MEDIA FRAME length of 256octets (e.g., MEDIA_256) to the M/S Node 1502. The M/S Node 1502 maytransfer the message to the MASTER Node 1504 with a MEDIA FRAME lengthof 256 octets (e.g., MEDIA_256).

FIG. 16 shows a second use case 1600 in which the PROTOCOL FRAME lengthis less than the MEDIA FRAME length. The 256-octet PROTOCOL FRAME may beentirely encapsulated into a 544-octet MEDIA FRAME. This frame istransmitted as a single 544 octet MEDIA FRAME. In the second use case1600, the communication channel between a MASTER Node 1604 and a M/SNode 1602 has a MEDIA FRAME length of 544 octets.

The transport between the M/S Node 1602 (routing device) to a SLAVE Node1606 (SLAVE target device) may have a MEDIA FRAME length constraint of256 octets. The M/S Node 1602 may forward the 544-octet MEDIA FRAME as a256-octet MEDIA FRAME to the SLAVE Node 1606. This is still a singletransfer case. The setup for both the sourcing and forwarding MASTER isshown in Table 17. A response from the SLAVE Node 1606 may betransferred to the M/S Node 1602 with a MEDIA FRAME length of 256octets. The M/S Node 1602 may transfer the response message to theMASTER Node 1604 with a MEDIA FRAME of 544 octets.

TABLE 17 MASTER MFC field setup for PROTOCOL_FRAME length < MEDIA FRAMElength Field Value Comments PTYPE.SIZE 2 MIMS_256 MFC.MFC 0 Setup forsingle frame transfer MFC.MFI 0 Don't care

Use cases in which the PROTOCOL FRAME length is greater than MEDIA FRAMElength may be best described by two use cases. The use cases may be adescribed as single frame to multi-frame forwarding and the multi-framelaunch to single-frame forwarding.

FIG. 17 shows a third use case 1700 that is a single-frame tomulti-frame forwarding use case. The third use case 1700 assumes a MEDIAFRAME size of 544 octets for the communication channel between asourcing MASTER 1704 and a routing MASTER 1702. The third use case 1700assumes a MEDIA FRAME size of 256 octets for the communication channelbetween the routing MASTER 1702 and a SLAVE Node 1706. In this use case,the sourcing MASTER 1704 may send a PROTOCOL FRAME matched to the MEDIAFRAME as a single frame transfer (e.g., MEDIA_544). The routing MASTER1702 may split the incoming frame into three MEDIA FRAMES fortransmission to the SLAVE Node 1706. Each MEDIA FRAME may have a lengthof 256 octets. The SLAVE Node 1706 may respond using a multi-framethree-frame transfer (each of length 256 octets) to the routing MASTER1702. The routing MASTER 1702 (or the forwarding device) may aggregatethe multi-frame transfer into a single frame transfer (of length 544octets) to the sourcing MASTER 1704 as a single-frame forwardingtransfer.

The setup of the frame control fields for the sourcing MASTER may be asshown in Table 18.

TABLE 18 Sourcing MASTER frame control settings for example in FIG. 17Field Value Comments PTYPE.SIZE 3 MIMS_544 MFC.MFS 0 Setup for singleframe transfer MFC.MFI 0 Don't care

The routing MASTER 1702 must split the 544-octet MEDIA FRAME into three256-octet MEDIA FRAMES. The setup of the frame control fields for therouting MASTER 1702 may be as shown in Table 19.

TABLE 19 Routing MASTER frame control settings for example in FIG. 17Field Value Comments PTYPE.SIZE 3 MIMS_544 MFC.MFS 2 Transfer three (3)frames MFC.MFI 0, 1, 2 Indices for frame[0 . . . 2]

The SLAVE Node 1706 may receive three 256-octet MEDIA FRAMES and mayre-assemble them into a single 544-octet PROTOCOL FRAME. The SLAVE Node1706, after processing the 544-octet PROTOCOL FRAME, may respond with a544 octet PROTOCOL FRAME. However; the SLAVE Node 1706 must split the544-octet PROTOCOL FRAME into three 256-octet MEDIA FRAMES. The setup ofthe SLAVE Node 1706 response frame may be as shown in Table 20.

TABLE 20 SLAVE Node frame control settings for example in FIG. 17 FieldValue Comments PTYPE.SIZE 3 MIMS_544 MFC.MFS 2 Three (3) MEDIA FRAMEtransfer MFC.MFI 0, 1, 2 Indices for frame[0 . . . 2]

FIG. 18 shows a fourth use case 1800 in which a sourcing MASTER 1804 maylaunch a PROTOCOL FRAME with a length larger than the communicationchannel MEDIA FRAME length. The fourth use case 1800 assumes a MEDIAFRAME size of 256 octets for the communication channel between thesourcing MASTER 1804 and a routing MASTER 1802. The fourth use case 1800assumes a MEDIA FRAME size of 544 octets for the communication channelbetween the routing MASTER 1802 and a SLAVE Node 1806. In this use case,the sourcing MASTER 1804 may send a PROTOCOL FRAME matched to the MEDIAFRAME as a three-frame 256-octet transfer (e.g., MEDIA_256). Each MEDIAFRAME may have a length of 256 octets. The routing MASTER 1802 mayassemble the incoming frames into a single 544-octet PROTOCOL FRAME fortransmission to the SLAVE Node 1806. The message may be sent to theSLAVE Node 1806 as a single 544-octet MEDIA FRAME. The SLAVE Node 1806may respond with a single 544-octet MEDIA FRAME to the routing MASTER1802. The routing MASTER 1802 (or the forwarding device) may split thesingle-frame 544-octet MEDIA FRAME into three 256-octet MEDIA FRAMEs fortransfer to the sourcing MASTER 1804 as a multi-frame forwardingtransfer. The sourcing MASTER 1804 may assemble the incoming frames intoa single 544-octet PROTOCOL FRAME for further processing.

The SLAVE Node 1806 may consume the 544-octet frame and respond with asingle 544-octet MEDIA FRAME transfer. The routing MASTER 1802 may splitthe incoming 544-octet MEDIA FRAME into three 256-octet MEDIA FRAMEtransfers to the sourcing MASTER 1804.

Table 21 shows the initial setup of the 256-octet MEDIA FRAMES sent bythe sourcing MASTER 1804.

TABLE 21 Sourcing MASTER frame control setup for example shown in FIG.18 Field Value Comments PTYPE.SIZE 3 MIMS_544 MFC.MFS 2 Transfer three(3) MEDIA FRAMES MFC.MFI 0, 1, 2 Indices for frame[0 . . . 2]

The routing MASTER 1802 may be configured to aggregate the three256-octet MEDIA FRAMES to form a single 544-octet PROTOCOL FRAME. Table22 shows the frame control setup for the routing MASTER 1802 and theSLAVE Node 1806 for aggregating the 544-octet MEDIA FRAME.

TABLE 22 Routing MASTER and SLAVE frame control setup for example shownin FIG. 18 Field Value Comments PTYPE.SIZE 3 MIMS_544 MFC.MFS 0 Singleframe transfer MFC.MFI 0 Don't care

Block transfers may be supported for all protocol types. All blocktransfers may operate using PROTOCOL FRAMES. All block transfers may bemoderated by the CSW and FTAG fields. See FIG. 12 and FIG. 14 for a viewof the CSW and FTAG bit-fields respectively.

A zero BLK value may be used to indicate a single frame transfer. Inthis case, the FTAG field may be a PROTOCOL FRAME tag or sequenceidentifier. The FTAG field may be any 16-bit value to uniquely identifya frame.

A non-zero BLK value may be used to indicate a block transfer. In thiscase, the FTAG field may be defined as two bit-fields. The bit-fieldsare the Block ID (BID) field and the Frame Count (FC) field.

The Block Transfer Mode may support a transfer of up to sixteen frames.Table 13 defines the field for configuring the MASTER BLK bit-fieldblock transfer request to setup a block transfer.

Given a specific frame size (PTYPE.SIZE), maximum frame transfers perblock (CSW.BLK) and the 10-bit block ID (FTAG.BID), the maximum payloadtransfer size per block (block transfer size, BTS) and the maximumnumber of octets transferred per session (max session size, MSS) may bedetermined.

Table 23 shows the relationship between FRAME SIZE (FSIZE) and the blocktransfer session size.

TABLE 23 The relationship between FRAME SIZE, payload, max blocktransfer and max block session size FSIZE PSIZE BTS MSS 128 96 1536 1.5M256 224 3584 3.5M 544 512 8192 8.0M 1056 1024 16384 16.0Mwhere FSIZE is the Frame Size (octets), PSIZE is the Payload Size(octets), BTS is the Block Transfer Size (octets), and MSS is theMaximum Session Size, (maximum # of octets transferred in one session).

FIG. 19 and FIG. 20 depicts two use cases for a five PROTOCOL FRAMEblock transfer. The two use cases are known as SEND TO SLAVE (CSW.CTL=1)and RECEIVE FROM SLAVE (CSW.CTL=0). FIG. 19 depicts the SEND TO SLAVEuse case 1900 and FIG. 20 depicts the RECEIVE FROM SLAVE use case 2000.

The process for a SEND block transfer may be initiated by the MASTER.For the duration of the block transfer, the MASTER sets the CSW.BLKbit-field to a non-zero value. The MASTER may follow certain rules for aSEND TO SLAVE block transfer. The MASTER sets the CSW.CTL=1 to indicatea SEND TO SLAVE block transfer. The MASTER sends CSW.BLK+1 PROTOCOLFRAMES to the SLAVE. The Frame TAG block ID (FTAG.BID) is set to aunique 10-bit number. The Frame TAG Frame Count, (FTAG.FC) is set tozero at the start of the block transfer. The FTAG.FC is incremented foreach PROTOCOL FRAME during the transfer.

The SLAVE will acknowledge using a single PROTOCOL FRAME for each SENDTO SLAVE block transfer. The SLAVE may follow certain rules for a SENDTO SLAVE block transfer. The SLAVE sends an ACK frame after receivingthe last FTAG.FC within the block. The SLAVE echoes the block ID(FTAG.BID) during the acknowledge. The SLAVE FTAG.FC response is don'tcare. The SLAVE block transfers ACK payload is dependent on the protocoltype.

FIG. 19 depicts a SEND TO SLAVE use case 1900. A time axis 1902 may bedefined that shows the progression of time during the SEND TO SLAVEtransfer. Depicted is the message transfer over time. A BID row 1904depicts the value of the FTAG.BID for certain time intervals. A FC row1906 depicts the value of the FTAG.FC for certain time intervals. AMaster Send Row 1908 represents certain time intervals during which theMASTER is transferring a frame. A SLAVE ACK row 1910 represents timeintervals during which the SLAVE sends an acknowledgment. In theexample, the MASTER is transferring five frames. The MASTER may sendmessage frames denoted as 0.0, 0.1, 0.2, 0.3, and 0.4. The Frame Countcorresponding to each of the message frames is shown as 0, 1, 2, 3, and4. After five frames are sent by the MASTER, the SLAVE responds with anACK message (denoted as ACK 0). In the example, the MASTER initiatesanother five-frame transfer with message frames denoted 1.0, 1.1, 1.2,1.3, and 1.4 with corresponding Frame Count of 0, 1, 2, 3, and 4. Thesecond five-frame transfer is followed by the SLAVE responding with anACK message (denoted ACK 1).

The MASTER device may determine a course of action for failed send blocktransfers. There are several scenarios in which an ERROR conditions mayarise. An error may be present when the last frame is not received bySLAVE. When the last frame is not received by the SLAVE, the SLAVE maybe configured to prevent sending an acknowledgement (ACK). In this case,the MASTER may timeout and take appropriate action.

An error may be present when the last frame is received by SLAVE, butnot all frames are received. An error may be present if all frames werereceived but failed an individual frame CRC32 check. For theseconditions, the SLAVE may be configured to send a block transfer NAKindication. The SLAVE block transfer NAK may be signaled by setting theCSW.CERR bit and signaling the CSW.SSTAT field as shown in Table 24.

TABLE 24 SEND-TO-SLAVE block transfer status, CSW.SSTAT fielddefinitions CSW.SSTAT Response CSW.CERR Description 0 ACK 0 Blocktransfer success 1 NAK 1 Last frame received, yet incomplete blockreceived — NONE — Last frame not received

A corrupted (bad CRC32) SLAVE ACK frame indicates a failed blocktransfer. It is recommended the MASTER resend the block on detection ofthis condition.

The SLAVE ACK block ID FTAG.BID response should match the block ID sentby the MASTER. The SLAVE ACK block frame count FTAG.FC response is setto the block transfer size as sent by the MASTER via the CSW.BLK field.

The SLAVE block transfer ACK payload is dependent on the protocol typeand block transfer status. The MASTER must ensure the SLAVE blocktransfer ACK response will fit in the payload of a SEND-TO-SLAVE ACKresponse.

FIG. 20 depicts a RECEIVE FROM SLAVE use case 2000. A time axis 2002 maybe defined that shows the progression of time during the RECEIVE FROMSLAVE transfer. Depicted is the message transfer over time. The processfor the receive block transfer may be initiated by the MASTER. For theduration of the transfer; the MASTER may set the CSW.BLK bit-field to anon-zero value. The MASTER may follow certain rules for a RECEIVE FROMSLAVE block transfer. The MASTER clears the CSW.CTL bit to zero toindicate a RECEIVE block transfer. The MASTER requests CSW.BLK+1PROTOCOL FRAMES from the SLAVE. The Frame TAG block ID (FTAG.BID) is setto a unique 10-bit number. The MASTER payload is dependent on thePROTOCOL TYPE and request.

A FC row 2010 depicts the value of the FTAG.FC for certain timeintervals. A Master Req Row 2004 represents certain time intervalsduring which the MASTER is requesting a block transfer. A SLAVE RSP row2006 represents time intervals during which the SLAVE sends messageframes. In the example, the MASTER is requesting five frames. The MASTERmay send a block request (BREQ 0). The SLAVE may respond by sendingmessage frames denoted as 0.0, 0.1, 0.2, 0.3, and 0.4. The Frame Countcorresponding to each of the message frames is shown as 0, 1, 2, 3, and4. After five frames are sent by the SLAVE, the MASTER may respond withanother block transfer request (BREQ 1). In the example, the SLAVEresponds with another five-frame transfer with message frames denoted1.0, 1.1, 1.2, 1.3, and 1.4 with corresponding Frame Count of 0, 1, 2,3, and 4.

After receiving the receive block transfer request, the SLAVE mayrespond with the requested number of PROTOCOL FRAMES. The SLAVE mayfollow certain rules for a RECEIVE FROM SLAVE block transfer. The SLAVEresponds with (CSW.BLK+1) PROTOCOL FRAMES. The SLAVE sets the CSW.BLK tothe value requested by the MASTER. The SLAVE sets the FTAG.BID responseto that requested by the MASTER. The first SLAVE transmitted frame setsthe FTAG.FC to zero. Subsequent transmitted PROTOCOL FRAMES mayincrement the FTAG.FC. The SLAVE payload is dependent on the PROTOCOLTYPE and MASTER request.

Any SLAVE can signal an error condition via an ERROR FRAME. Errorconditions may occur during any CONTROL or DATA plane transaction. ASLAVE may also signal an unsolicited error condition. The unsolicitederror condition is known as an EVENT error condition.

The Control and Status Word (CSW) has both a Control Plane and DataPlane error signaling bit. Each of these bits, in conjunction with theCTL bit indicates up to four SLAVE error responses. Table 25 shows eachof the Control and Data Plane error signaling conditions.

TABLE 25 Error signalling conditions CERR DERR CTL Error condition 0 0 XNormal Frame transport, NO error 1 0 0 Control Plane get-request error 10 1 Control Plane set-response error 0 1 0 Data Plane get-request error0 1 1 Data Plane set-response error 1 1 X reservedIn Table 25, CERR is the Control Plane Error bit field, DERR is the DataPlane Error bit field, CTL is the GET/SET transfer bit field, and Xindicates that the value does not matter.

The error signaling layout for the CSW is also shown in FIG. 21. FIG. 21shows the recommended values for each of the bit fields. Also shown arethe SSTAT fields as an orthogonal set of Control Plane Error (CERR) anda Data Plane Error (DERR) status codes. A first bit-field definition2104 may generally define the positions of bits. An SSTAT field may be aSLAVE status field and may take on values indicative of a control planeerror code (ECCP) and a data plane error code (ECDP). The E field may bean event notification. The CERR field may indicate that a controltransfer was successful or an error occurred. The DERR field mayindicate that a data transfer was successful or an error occurred. TheCTL field may indicate a GET or SET response. The BLK field may beechoed for a set response and zero for a get response.

A second bit-field 2106 may be an example of a control plane get-requesterror. A third bit-field 2018 may be an example of a control planeset-request error. A fourth bit-field 2110 may be an example of a dataplane get-request error. A fifth bit field 2112 may be an example of adata plane set-request error.

Upon signaling an error, the payload may contain an error frame. Theformat of the error frame 2200 may be as shown in FIG. 22. Individualoctets within the frames may be indexed by a hexadecimal octet positionindex 2202 and/or a decimal octet position index 2204. Octets within theerror frame may also be indexed by a hexadecimal address 2206 and/or adecimal address 2208. For example, the position within the error frameof any byte of information may be determined by using the hexadecimaloctet position index 2202 and the hexadecimal address 2206. The errormessage frame may include four 32-bit messaging fields and a 16-octetreserved field with the rest of the payload designated as astring-oriented descriptor buffer. The first messaging field (ERR_CODE)may be an application-specific error code. The second (E_HINT1), third(E_HINT2), and fourth (E_HINT3) fields may be developer-assigned hints.The string-oriented descriptor buffer may hold a NUL terminatedcharacter string. This string may carry any extra information fordiagnostics capability.

There may be a total of 2048 possible common protocols available forMIMS. The protocols may be reserved in the range 0 to 0x07FF. All commonprotocols may use a 6-octet MIMS Addressing (MA) with routing rules. Anynew common protocols may be added later. All devices may advertise theprotocols known via a CAPABILITIES request.

A list of known common protocols may be defined as shown in Table 26.Each protocol and behavior is described in later sections of thisdocument.

TABLE 26 Common PROTOCOLS for the MIMS compliant nodes VALUE PROTOCOLAddressing Description 0x0000 CAPABILITY MA GET ALL protocolcapabilities 0x0001 PROPERTY MA GET/SET property-value pair

A top-level MASTER may communicate to any Node within its routing treeusing any COMMON protocol with MIMS Addressing. FIG. 23 shows a map 2300of a 32-octet MIMS frame header 2306. Individual octets within the MIMSframe header 2306 may be indexed by a hexadecimal octet position index2302 and/or a decimal octet position index 2304. Table 27 introduces theMIMS Address (MA) and routing instance ID (RIID) fields. The remainingfields may function as previously described herein.

TABLE 27 A summary of the MAC addressing with routing information FieldOffset Width Description MA_DST 14 6 MIMS Address, destination MA_SRC 206 MIMS Address, source RIID 26 2 Routing Instance Identifier

Within its local domain, each Node may bind an access method to a MIMSaddress. When a request is made to a specific routing MASTER, the mastermay look up and execute the proper access method to send and receiveframes to the Node.

FIG. 24 shows a generic view of a typical MASTER-SLAVE network 2400. Inthis example, each of the MASTERS communicates to a SLAVE using aspecific physical and link layer technology. One of the conceptsintroduced by the MIMS session layer is to allow bridging or routingbetween the various Local Domains (LD). This bridging between the LocalDomains is affected via the MIMS addressing along with the RoutingInstance Identifier (RIID) tag.

The M/S network 2400 may include a first Slave Master 2408 (MA_2). Thefirst Slave Master 2408 may be configured to learn and store all routesof communication for connected slave nodes or master/slave nodes. Thefirst Slave Master 2408 may be in communication with a first group ofSlave Nodes 2410 (MA_3, MA_4, MA_5, MA_6, MA_7, and MA_9). The firstSlave Master 2408 may be in communication with a second Slave Master2412 (MA_8).

The M/S network example 2400 may include a USB Terminal 2404 that may beconfigured as a Master node. The USB Terminal 2404 may be configured tolearn and store all routes of communication for connected devices. Inthis example, the USB terminal 2404 is connected to the first SlaveMaster 2408.

The second Slave Master 2412 may be in communication with a second groupof Slave Nodes 2416 (MA_10, MA_12, MA_13, MA_14) and a third SlaveMaster 2418 (MA_11).

The third Slave Master 2418 may be in communication with a third groupof Slave Nodes 2420 (MA_15, MA_17, MA_18) and a fourth Slave Master 2422(MA_16).

The third Slave Master 2418 may be configured to learn and storecommunication routes for all connected Slave Nodes 2420. The third SlaveMaster 2418 may be configured to learn and store communication routesfor any Slave Masters to which it communicates as a Master. In thisexample, the third Slave Master 2418 may be configured to learn andstore communication routes associated with the fourth Slave Master 2422.

The second Slave Master 2412 may be configured to learn and storecommunication routes for all connected Slave Nodes 2416 and SlaveMasters (e.g., 2418) that operate in Slave Mode with respect to thesecond Slave Master 2412.

The first Slave Master 2408 may be configured to learn and storecommunication routes for all connected Slave Nodes 2410 and SlaveMasters (e.g., 2412) that operate in Slave Mode with respect to thefirst Slave Master 2408.

The Slave/Master Nodes may have certain features that enable routing.All Slave/Master Nodes are capable of routing. All Slave/Master Nodesmay have any number of MASTER or SLAVE devices connected to it. All SSlave/Master Nodes may learn the routes for its LD and all subsequentLDs. Each Slave/Master Node shall have a physical-dependent accessmethod attached to a specific route.

FIG. 25 shows the MIMS (S/M) addressing features 2500 using a SlaveMaster 2502 that is configured as a 4-port MASTER and a 4-port SLAVEnode as an example. The figure depicts how the routing of any MASTERrequest may be accommodated by the (S/M) node. The system may followcertain rules for MASTER to SLAVE MAC address forwarding. Any frameoriginated by a node may be assigned a RIID value of zero. Any routedframe may have a non-zero RIID value. An incoming frame is routed inresponse to the MIMS destination address not being equal to the (S/M)address and the MIMS destination address being equal to the learnedrouting MIMS address. The (S/M) node may lookup an existing RIID tagusing (e.g., a reverse lookup) the SOURCE MIMS address, the SOURCE portID, and/or the SOURCE RIID tag. If the RIID entry does not exist, thenode generates a new and unique RIID tag (e.g., new RIID table entry)and binds this value to the SOURCE MIMS address, the SOURCE port ID, andthe SOURCE RIID tag. The (S/M) node may substitute the RIID tag andforward the frame to the proper SLAVE port.

Likewise, there may be a set of rules for any received frame. In thiscase, the RIID establishes the routing or frame handling rules. TheSLAVE to SOURCE MIMS address reception may follow certain rules. Anyreceived frame with the RIID tag of zero is consumed by the node. Anyreceived frame with a non-zero RIID tag is forwarded to the SOURCE portusing the RIID tag. The (S/M) device may look up the RIID entry usingthe incoming RIID tag SOURCE MIMS address, SOURCE port ID, and SOURCERIID tag. The (S/M) node may substitute the stored RIID tag and forwardthe packet to the stored SOURCE port ID.

A first set of Slave Master Nodes 2504 may be in communication with theSlave Master 2502 via one or more Slave ports. The Slave Master 2502 maybind a unique RIID to forwarded MIMS addressed frames using the SOURCEaddress and the SLAVE port ID. The Slave Master 2502 may be incommunication with a first group of Slave Nodes 2506 via one or moreMaster ports. The Slave Master 2502 may be in communication with asecond Slave Master 2508 via one of the Master ports.

The Slave Master 2502 may learn all routes under its local domain (e.g.,Slave Nodes 2506) and subsequent local domains of connected Slave/MasterNodes (e.g., 2508). The Slave Master 2508 may be connected to variouslocal domain devices 2510.

The rules for forwarding and receiving any RIID stamped frame may use anRIID routing table. The purpose of this table is to establish theupstream routes for any downstream routed frame. In the event of anySLAVE or MASTER device losing connection, the RIID table requires eachentry to be time-stamped and aged out. The aging time for the RIID tableis dependent on the Local Domain and all connections to a specific (S/M)device. Therefore, it is optional, yet desirable to allow the aging timeparameter for a specific (S/M) device to be configured at run-time.

Each device may be addressed by a 6-octet MIMS address. The address maybe either a statically assigned MIMS address or a dynamically assignedMIMS address.

All MIMS nodes may support the CAPABILITY protocol type. The CAPABILITYprotocol type allows any MASTER to determine the list of common andapplication protocols that are supported by a particular node. TheMASTER may set the PTYPE.PROTOCOL field to zero and the payload to allzero values to issue a CAPABILITY request. Only GET requests may behonored by the CAPABILITY request. The MASTER may set the CSW.CMDbit-field to zero (GET) in order to issue a CAPABILITY request.

The SLAVE may process and respond to the CAPABILITY request. The SLAVEmay indicate any associated capabilities. The CAPABILITY request mayinclude a field for the Universally Unique Identifier (UUID) and otherdescriptor fields as shown in Table 28. The CAPABILITY response fieldsmay always be reported in network byte order.

TABLE 28 Format of the CAPABILITY request message Offset Size NameDescription 0 4 Reserved Reserved, set to zero (0) 4 16 UUID UniversallyUnique Identifier 20 4 DDW Device Descriptor Word 24 2 MFS Media FrameSize 26 2 MBS Maximum Block Transfer Size 28 2 PLSIZE Protocol List Size30 PLSIZE × 2 PLIST Protocol type List (list of protocol types)In Table 28, all sizes may be in octets. The Offset column represents anoffset in octets from the start of the PAYLOAD section. UUID is theUniversally Unique Identifier that is a unique 128-bit word whichidentifies the node. MBS is a Maximum Block Transfer size that definesthe maximum payload octets allowed in block transfer. DDW is the DeviceDescriptor Word that may be used to notify the MASTER of any extrainformation. PLSIZE is a total number of protocol types supported bythis device. PLIST is an array of protocol types supported by thisdevice.

The UUID is the Universally Unique Identifier. This is a 128-bit wordthat can guarantee a unique identification for the node. Some of thepurposes for using the UUID are to guarantee a unique 128-bitapplication identity and to allow the Host Services Gateway to acquirethe correct Application Descriptor Sheet (schema).

The Device Descriptor Word contains bit-fields which may yield moreinformation about a specific device. FIG. 26 shows the format 2600 ofthe DDW 2604. Individual bits within the word may be indexed by adecimal bit position index 2602.

A Master bit-field (MS) indicates whether the node is SLAVE/MASTER (SM)capable, or a SLAVE only. A one in this bit-field indicates that thedevice is SM. A zero indicates that this device is SLAVE only.

A Routing capable bit-field (RC) indicates whether this node has anyMIMS routing capability. Even though all SM devices may always haverouting capability, some SLAVE only devices may have some MIMS routingcapability.

A payload byte-ordering bit-field (BO) specifies the byte orderingcapability of the node for the payload. The byte ordering of the MIMSheader may always be network byte order (BIG ENDIAN). The payload byteordering is device dependent. A one in this bit-field indicates that thenode uses BIG ENDIAN byte ordering. A zero indicates that the node usesLITTLE ENDIAN byte ordering for the payload.

A loader/application mode bit field (LD) defines a mode of the node. Anynode can be in loader or application mode. The loader mode functions areused to support field upgrades of the firmware. A one in this bit-fieldindicates the node is in LOADER mode. A zero in this bit-field indicatesthe node is in APPLICATION mode.

Referring again to Table 28, a media frame size bit-field (MFS)specifies the number of octets required to support MEDIA FRAME transfersfor the particular node and physical interface. All local transports maybe performed via MEDIA FRAME transfers using a fixed MFS size.

A maximum block transfer size bit-field (MBS) specifies the maximumblock transfer size of the node. Some MIMS capable nodes may have memoryresource constraints and may have some limited capability to transferblocks of information. The Maximum Block Transfer MBS field is used todescribe this limitation to a MASTER. The MBS field contains the maximumnumber of octets allowed in the total payload for any block transfer.

A protocol list size (PLSIZE) bit-field indicates the total number ofPROTOCOLS that the device can interpret on its Local Domain. This numbermay include CAPABILITY protocol type as part of the protocol list.

A protocol type list (PLIST) bit-field may be a list of all theprotocols that the node can support. The size of the list is PLSIZEelements or PLSIZE×2 octets long.

The MIMS addressable PROPERTY protocol type allows a MASTER to get orset a list of values that are associated with a list of PAMS properties.Properties are hash-tags which are defined in a dictionary. For MIMS,the properties may be defined as a set of hash-tags in a PAMS ADS fileassociated with the particular node.

The property dictionary defines the association of a property hash-tagwith a set of types. In this way, any MASTER, with the ADS dictionarycan retrieve or set information on a particular node.

To request or set a particular property, the node may construct aproperty hash record (PHR). The record may consist of two fields. Thesefields may be the Property tag (PROPERTY) and the Instance Identifier(IID). FIG. 27 shows the format 2700 of the Property Hash Record 2704 asindexed by an octet position index 2702.

A property tag bit-field (PROPERTY) may be a 32-bit value that isdefined in the ADS dictionary. This dictionary may be stored in arepository and be retrieved using the node UUID. An instance identifierbit-field (IID) may define a value that is used to access arrays, partsof arrays or scalars. FIG. 28 depicts a possible format 2800 for the IIDfield 2804 as indexed by a bit-position index 2802. A brief descriptionof the IID bit-fields is shown in Table 29.

TABLE 29 Bit-field definitions of the IID field Mnemonic Name # bitsDescription IDX Instance Index 10 Instance Index, Starting index for aproperty value array IC Instance Count 6 Total number of values toretrieve

The instance index (IDX) bit-field may be a zero-referred starting indexin a property value array. The IDX value may be set to zero, if theproperty value is a scalar. Otherwise, the IDX value is set to thestarting index into the array.

The instance count (IC) bit-field sets up the total number of values toset or get. The IC value may be set to one if the property represents ascalar. A zero value for the IC value may have special significance. Aninstance identifier of 0.0 may be configured to return the currentnumber of available elements represented by the property.

VECTOR LISTS (arrays) may be represented internally as a list ofinstances. There may be two element count parameters. The parameters maybe referred to as the MAX_COUNT (or m_count) parameter and theVECTOR_COUNT (or v_count) parameter.

The m_count parameter may contain the MAXIMUM number of elements thatare possible in the list. This parameter may be fixed and may be exposedas part of the PAMS mark-up. The v_count parameter may contain the totalnumber of valid elements currently in the list. This parameter may haveany value from zero to (m_count−1) at run-time.

The internal vector list may always start with an index of zero. Anyelement can be accessed by setting up the property hash record, PHR,instance identifier, (IID) value.

Scalars may always be represented as a single instance. The number ofelements available (MAX or VALID) may always be equal to one. Any SCALARrequest with an instance count, (IC) greater than one may cause theSLAVE to return an ERROR FRAME.

To retrieve a set of property values, the MASTER or CLIENT may request alist of property values. To do this, the MASTER may clear the CSW.CTLbit to zero and send the total property count and a list of propertyhash records, PHR list. The payload format for this request is shown inTable 30.

TABLE 30 Format for a GET PROPERTY request. Offset Size Name Description0 2 N Total number of property values to retrieve 2 6 PHR₀ Property HashRecord [0] 8 6 PHR₁ Property Hash Record [1] . . . . . . . . . MoreProperty records 6 × (N − 1) 6 PHR_((N−1)) Last Property Record

The targeted SLAVE may respond with a GET Response. In this case, theCSW.CTL bit is still cleared (get-response) and the SLAVE sends a listof PHR values followed by the list of values. The format for theresponse is shown in Table 31.

TABLE 31 Format for a GET PROPERTY response Offset Size Name Description0 2 N Total number of properties 2 6 PHR₀ Property Hash Record [0] 8 6PHR₁ Property Hash Record [1] . . . . . . . . . More property hashrecords 6 × (N − 1) 6 PHR_((N−1)) Last Property Hash Record 6 × Nsizeof(VALUE₀) VALUE₀ VALUE 0 (6 × N) + sizeof(VALUE) sizeof(VALUE₁)VALUE₁ VALUE 1 . . . sizeof(VALUE) VALUE More values (6 × N) +sizeof(VALUE_(N−1)) VALUE_((N−1)) Last value Σ{sizeof(VALUE_(i))}

Within each property response; the CLIENT may interrogate a list ofinstances for any VECTOR LIST property type. The format of the VECTORLIST get-response sub-field is shown in Table 32. In this example, thesizes are all uniform because each of the instances is identical insize.

TABLE 32 GET-RESPONSE vector list sub-field get-response format OffsetSize Name Description 0 2 rc return count of valid instances 2sizeof(VALUE) VALUE_(idx) VALUE @ idx . . . . . . VALUE More VALUES 2 +(ic − 1) × sizeof(VALUE) VALUE_(ic−1) VALUE @ (ic − 1) sizeof(VALUE)

The SLAVE device may return the number of VECTOR LIST propertiesrequested by the IID instance (ic) count. This number may be referred toas the return count (rc) value. Any element instances between thev_count and the m_count range are represented by a NUL-filled instance,(e.g., an instance filled with zeros).

The return count value, (rc) may be dependent on the requested index(idx), instance count (ic) and vector count (v_count) values. The sum ofthe (ic) and the (idx) parameters may be referred to as the returnlength index (RLI). The RLI definition may be as follows.RLI≡idx+ic  (2)

The RETURN COUNT (rc) value may be dependent on the return length index(RLI). The calculation may use the following set of inequalities:IF {RLI<m_count} THEN TX ERROR FRAME  (3)ELSEIF {RLI>v_count} THEN rc=v_count−idx  (4)ELSE rc=ic  (5)

A set of value(s) or the number of elements may be queried via aget-request IID. A non-zero instance count may get a SCALAR or a VECTORLIST. A zero-instance count may get the number of valid elements(v_count) for the property. Table 33 shows the GET-REQUEST rules forSCALAR properties.

TABLE 33 GET-REQUEST SCALAR instance identifier rules IID.idx IID.icRETURN size/comments 0 0 1 (unsigned short), the number one (1) 0 1SCALAR (size depends on type), scalar value >0 0 ERROR An ERROR FRAMEX >1 ERROR An ERROR FRAME

Table 34 shows the GET-REQUEST rules for VECTOR LIST properties.

TABLE 34 GET-REQUEST VECTOR LIST instance identifier rules IID.idxIID.ic RETURN size/comments X 0 v_count (unsigned short), VECTOR LISTcount idx ic VECTOR [rc + list of values]; rc is (unsigned short), LISTINSTANCE size depends on type.

To modify or set a list of property values, the MASTER can send a SETRequest. To do this, the master sets the CSW.CTL bit to a one (setrequest) and sends a list of PHR: VALUE pairs. This operation works onproperties that are defined with the writable attribute. Otherwise, theSLAVE responds with an ERROR FRAME. The payload format for the SETRequest is shown in Table 35.

TABLE 35 Format for a SET property request Offset Size Name Description0 2 N Total number of properties 2 6 PHR₀ Property Hash Record [0] 8 6PHR₁ Property Hash Record [1] . . . . . . . . . More Property HashRecords 6 × (N − 1) 6 PHR_((N−1)) Last Property Hash Record 6 × Nsizeof(VALUE₀) VALUE₀ VALUE 0 (6 × N) + sizeof(VALUE) sizeof(VALUE₁)VALUE₁ VALUE 1 . . . sizeof(VALUE) VALUE More values (6 × N) +sizeof(VALUE_(N−1)) VALUE_((N−1)) Last value Σ{sizeof(VALUE_(i))}

To confirm the successful SET operation, the SLAVE may send a list ofPHR values back to the requesting MASTER to confirm that the SEToperation succeeded. The SLAVE may set the CSW.CTL bit to a one (setconfirmation). The payload format for the SET Response is shown in Table36.

TABLE 36 Format for a SET property response Offset Size Name Description0 2 N Total number of set properties confirmed 2 6 PHR₀ Property HashRecord [0] 8 6 PHR₁ Property Hash Record [1] . . . . . . . . . MoreProperty Hash Records 6 × (N − 1) 6 PHR_((N−1)) Last Property HashRecord

A CLIENT may set a list of instances for any VECTOR LIST property. Theformat of the VECTOR LIST set-request sub-field is shown in Table 37.

TABLE 37 VECTOR LIST property set-request sub-field format Offset SizeName Description 0 2 ic instance count 2 sizeof(VALUE) VALUE_(idx) VALUE@ idx . . . . . . VALUE More VALUES 2 + (ic − 1) × sizeof(VALUE)VALUE_(ic−1) VALUE @ (ic − 1) sizeof(VALUE)

Table 37 shows the first field in the VECTOR LIST property set-requestas the instance count (ic) value. This may be the same value ascontained in the IID.ic instance count field.

The VECTOR LIST and SCALAR set-requests may not support anymodifications of the vc_count value. The vc_count value may always be aREAD-ONLY parameter. The list of rules for a set-request on a SCALARproperty is shown in Table 38.

TABLE 38 SCALAR set-request IID rules IID.idx IID.ic actionsize/comments 0 1 Set scalar (size depends on type), scalar value X 0 TxERROR FRAME Attempt to set v_count X >1 Tx ERROR FRAME Attempt to set anon-existent instance

Any writing to a non-existent instance may generate an error frame.Since modification of the vc_count value is not supported, any VECTORLIST set-requests with a zero-instance count (ic) may also generate anerror. Table 39 shows a list of rules for a set-request on a VECTOR LISTproperty

TABLE 39 VECTOR LIST set-request IID rules IID.idx IID.ic Actionsize/comments idx ic Set (unsigned short), VECTOR LIST instance count X0 Tx ERROR (unsigned short), FRAME VECTOR LIST count X (idx +ic)>v_count Tx ERROR Attempt to write to a FRAME non-existent instance

The data transport system that is described herein provides improvementsin the operation of networked computer systems. The system describedreduces the burden on developers during development. The PAMS may begenerated and reside in the solution gateway nodes. The PAMS data istransferred to higher-level systems that can dynamically render adatabase of variables that are available in the node. This processhappens automatically whenever the nodes are reprogrammed. In thismanner, MASTER nodes do not need reprogramming to recognize changes tothe data interface for a connected node. The described improvements maybe especially useful in large networked systems as reprogramming allnodes would be difficult and require some down-time. The describedimprovements also allow for simple integration of new nodes. New nodesmay be brought online and data from the node may be readily available toall nodes in the system.

Control logic or functions performed by controller may be represented byflow charts or similar diagrams in one or more figures. These figuresprovide representative control strategies and/or logic that may beimplemented using one or more processing strategies such asevent-driven, interrupt-driven, multi-tasking, multi-threading, and thelike. As such, various steps or functions illustrated may be performedin the sequence illustrated, in parallel, or in some cases omitted.Although not always explicitly illustrated, one of ordinary skill in theart will recognize that one or more of the illustrated steps orfunctions may be repeatedly performed depending upon the particularprocessing strategy being used. Similarly, the order of processing isnot necessarily required to achieve the features and advantagesdescribed herein, but are provided for ease of illustration anddescription. The control logic may be implemented primarily in softwareexecuted by a microprocessor-based vehicle, engine, and/or powertraincontroller, such as controller. Of course, the control logic may beimplemented in software, hardware, or a combination of software andhardware in one or more controllers depending upon the particularapplication. When implemented in software, the control logic may beprovided in one or more computer-readable storage devices or mediahaving stored data representing code or instructions executed by acomputer to control the vehicle or its subsystems. The computer-readablestorage devices or media may include one or more of a number of knownphysical devices which utilize electric, magnetic, and/or opticalstorage to keep executable instructions and associated calibrationinformation, operating variables, and the like.

The processes, methods, or algorithms disclosed herein can bedeliverable to/implemented by a processing device, controller, orcomputer, which can include any existing programmable electronic controlunit or dedicated electronic control unit. Similarly, the processes,methods, or algorithms can be stored as data and instructions executableby a controller or computer in many forms including, but not limited to,information permanently stored on non-writable storage media such asRead Only Memory (ROM) devices and information alterably stored onwriteable storage media such as floppy disks, magnetic tapes, CompactDiscs (CDs), Random Access Memory (RAM) devices, and other magnetic andoptical media. The processes, methods, or algorithms can also beimplemented in a software executable object. Alternatively, theprocesses, methods, or algorithms can be embodied in whole or in partusing suitable hardware components, such as Application SpecificIntegrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs),state machines, controllers or other hardware components or devices, ora combination of hardware, software and firmware components.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms encompassed by the claims.The words used in the specification are words of description rather thanlimitation, and it is understood that various changes can be madewithout departing from the spirit and scope of the disclosure. Aspreviously described, the features of various embodiments can becombined to form further embodiments of the invention that may not beexplicitly described or illustrated. While various embodiments couldhave been described as providing advantages or being preferred overother embodiments or prior art implementations with respect to one ormore desired characteristics, those of ordinary skill in the artrecognize that one or more features or characteristics can becompromised to achieve desired overall system attributes, which dependon the specific application and implementation. These attributes mayinclude, but are not limited to cost, strength, durability, life cyclecost, marketability, appearance, packaging, size, serviceability,weight, manufacturability, ease of assembly, etc. As such, embodimentsdescribed as less desirable than other embodiments or prior artimplementations with respect to one or more characteristics are notoutside the scope of the disclosure and can be desirable for particularapplications.

What is claimed is:
 1. A data transport system comprising: at least onenode including a first processor coupled to a first memory andconfigured to communicate with local devices via independent nativeprotocols and to store a protocol agnostic metadata schema (PAMS) thatdefines a data interface for process variables, wherein the at least onenode is identified by an identifier that changes when the data interfacechanges; and at least one computing system including a second processorcoupled to a second memory and programmed to, communicate with at leastone application and the at least one node using a media independentmessaging service (MIMS) that is layered over respective communicationprotocols associated with the at least one application and the at leastone node, query the at least one node for the identifier and, responsiveto the identifier not matching a stored identifier, request the at leastone node to transfer metadata corresponding to the data interface;receive, from the at least one node, the metadata corresponding to thedata interface and dynamically render a web application programminginterface (API) that allows users of the at least one application toaccess the process variables, and responsive to requests from the atleast one application to access the process variables, transfer therequests to the at least one node and transfer responses from the atleast one node to the at least one application.
 2. The data transportsystem of claim 1 wherein the PAMS is encoded in extensible markuplanguage (XML).
 3. The data transport system of claim 1 wherein the atleast one application is executed on a terminal that is in communicationwith the at least one computing system.
 4. The data transport system ofclaim 1 wherein the PAMS is generated based on one or more enumeratedtypes defined in one or more source code files for the at least onenode.
 5. The data transport system of claim 1 wherein the PAMS isconfigured to bind instances of the process variables to a record thatdescribes the data interface of the process variables.
 6. The datatransport system of claim 1 wherein the at least one application mayaccess the process variables by requesting respective values associatedwith the process variables and by setting respective values associatedwith the process variables using a message structure defined by theMIMS.
 7. The data transport system of claim 1 wherein the processvariables are mapped to software variables used by the at least onenode.
 8. A node for use in a data transport system comprising: acontroller including a processor coupled to a storage memory andprogrammed to store a protocol agnostic metadata schema (PAMS) thatdefines a data interface for process variables, identify the node by anidentifier that changes when the data interface changes; communicatewith a server over a first communication channel using a mediaindependent messaging service (MIMS) layered over a first communicationprotocol, communicate with one more process devices via a nativeprotocol that is independent of the MIMS, respond to queries from theserver for the identifier, respond to requests from the server totransfer metadata associated with the data interface to the server, andrespond to requests from the server for access to process variables thatare defined in the data interface.
 9. The node of claim 8 wherein thePAMS is encoded in extensible markup language (XML).
 10. The node ofclaim 8 wherein the PAMS is generated based on one or more enumeratedtypes defined in one or more source code files for the node.
 11. Thenode of claim 8 wherein the PAMS is configured to bind instances of theprocess variables to a record that describes the data interface of theprocess variables.
 12. The node of claim 8 wherein the controller isconfigured to communicate with at least one other node over a secondcommunication channel using the MIMS layered over a secondcommunications protocol and programmed to transfer messages using theMIMS between the first communication channel and the secondcommunication channel.
 13. A host services gateway for use in a datatransport system comprising: a controller including a hardware processorcoupled to a storage memory and programmed to establish a communicationconnection with at least one node, query the at least one node for anidentifier for a protocol agnostic metadata schema (PAMS) that defines adata interface for process variables of the at least one node, whereinthe identifier changes when the data interface changes, communicate withthe at least one node and at least one application using a mediaindependent messaging service (MIMS) that is layered over respectivecommunication protocols associated with the at least one application andthe at least one node, request, responsive to the identifier notmatching previously stored identifiers, the at least one node to sendmetadata corresponding to the data interface, and dynamically render aweb application programming interface (API) from received metadata andexpose the web API to the at least one application.
 14. The hostservices gateway of claim 13 wherein the controller is furtherprogrammed to transfer values of process variables between the at leastone application and the at least one node according to the web API. 15.The host services gateway of claim 13 wherein the respectivecommunication protocols include hypertext transfer protocol (HTTP) thatis associated with the at least one application.
 16. The host servicesgateway of claim 13 wherein the controller is further programmed tostore the metadata and web API associated with the at least one node.